研究者データベース

研究者情報

マスター

アカウント(マスター)

  • 氏名

    佐分利 亘(サブリ ワタル), サブリ ワタル

所属(マスター)

  • 農学研究院 基盤研究部門 生物機能化学分野

所属(マスター)

  • 農学研究院 基盤研究部門 生物機能化学分野

独自項目

syllabus

  • 2021, バイオテクノロジー学特論, Advanced Biotechnology, 修士課程, 農学院, バイオテクノロジー、糖質酵素、mRNA分解、植物ウイルスベクター、糖質生合成、酵素改変、木質資源、食品機能、微生物資源、微生物バイオプロセス、技術・データ駆動型
  • 2021, バイオテクノロジー学特論演習, Advanced Seminar on Biotechnology, 修士課程, 農学院, バイオテクノロジー,生物利用・物質生産
  • 2021, 大学院共通授業科目(一般科目):自然科学・応用科学, Inter-Graduate School Classes(General Subject):Natural and Applied Sciences, 修士課程, 大学院共通科目, バイオテクノロジー、糖質酵素、mRNA分解、植物ウイルスベクター、糖質生合成、酵素改変、木質資源、食品機能、微生物資源、微生物バイオプロセス、技術・データ駆動型
  • 2021, 食品安全・機能性開発学特論, Advanced Safety and Function of Food, 修士課程, 農学院, 食品安全性、予測微生物、食料確保と安全性、植物由来機能性食品、微生物由来機能性食品、腸内細菌叢の改変に基づいた機能性食品、食肉由来機能性食品
  • 2021, 食品安全・機能性開発学特論演習, Advanced Seminar on Safety and Function of Food, 修士課程, 農学院, 食品の安全、予測微生物学、食料確保と安全性、植物由来機能性食品、微生物由来機能性食品、腸内細菌叢の改変に基づいた機能性食品、食肉由来機能性食品
  • 2021, 大学院共通授業科目(一般科目):自然科学・応用科学, Inter-Graduate School Classes(General Subject):Natural and Applied Sciences, 修士課程, 大学院共通科目, 食品安全性、予測微生物、食料確保と安全性、植物由来機能性食品、微生物由来機能性食品、腸内細菌叢の改変に基づいた機能性食品、食肉由来機能性食品
  • 2021, 生物機能化学演習Ⅱ, Seminar on Bioscience and Chemistry II, 学士課程, 農学部, 専門関連英文原書精読
  • 2021, 生物機能化学実験Ⅲ, Laboratry Work on Bioscience and Chemistry III, 学士課程, 農学部, 酵素反応、反応速度論、タンパク質精製、電気泳動
  • 2021, 生物化学Ⅰ, Biochemistry I, 学士課程, 農学部, 生化学,生体成分,糖質,アミノ酸,タンパク質,酵素,補酵素,ビタミン,脂質,核酸
  • 2021, 生物化学Ⅱ, Biochemistry II, 学士課程, 農学部, 代謝,エネルギー,解糖系,トリカルボン酸回路,電子伝達系,酸化的リン酸化,糖新生,ペントースリン酸経路,脂質代謝,光合成,カルビンサイクル,窒素代謝,尿素サイクル
  • 2021, 生物化学Ⅲ, Biochemistry III, 学士課程, 農学部, タンパク質,酵素,応用糖質科学,糖質の構造,糖質の機能,糖質の代謝,糖質の合成,糖質の利用

researchmap

プロフィール情報

学位

  • 博士(農学)(2006年03月 北海道大学)

プロフィール情報

  • 佐分利, サブリ
  • 亘, ワタル
  • ID各種

    201201038539083300

業績リスト

研究キーワード

  • 蛋白質工学   応用微生物学   糖質合成   酵素化学   応用生物化学   

研究分野

  • ライフサイエンス / 応用生物化学

経歴

  • 2020年07月 - 現在 北海道大学 大学院農学研究院 准教授
  • 2019年04月 - 2020年06月 北海道大学 大学院農学研究院 講師
  • 2010年10月 - 2019年03月 北海道大学 大学院農学研究院 助教
  • 2006年04月 - 2010年09月 日本食品化工株式会社 研究所 研究員

学歴

  • 2001年04月 - 2006年03月   北海道大学   大学院農学研究科
  • 1997年04月 - 2001年03月   北海道大学   農学部   応用生命科学科

委員歴

  • 2021年03月 - 現在   日本農芸化学会   英文誌編集委員
  • 2017年09月 - 現在   応用糖質科学会   Journal of Applied Glycoscience編集委員
  • 2011年04月 - 2013年03月   日本農芸化学会   北海道支部会計幹事

受賞

  • 2020年09月 日本応用糖質科学会 奨励賞
     
    受賞者: 佐分利 亘
  • 2018年09月 日本応用糖質科学会 ポスター賞
     
    受賞者: 佐分利 亘
  • 2017年09月 日本応用糖質科学会 ポスター賞
     
    受賞者: 佐分利 亘
  • 2017年04月 Congress on Gastrointestinal Function James Russel Award
     
    受賞者: 佐分利 亘
  • 2016年09月 日本応用糖質科学会 ポスター賞
     
    受賞者: 佐分利 亘
  • 2015年03月 日本農芸化学会 農芸化学奨励賞
     
    受賞者: 佐分利 亘
  • 2014年10月 植物化学調節学会 ポスター賞
     
    受賞者: 佐分利 亘
  • 2013年06月 酵素応用シンポジウム 研究奨励賞
     
    受賞者: 佐分利 亘

論文

  • Wataru Saburi, Takayoshi Tagami, Takuya Usui, Jian Yu, Toyoyuki Ose, Min Yao, Haruhide Mori
    Food Bioscience 61 104516 - 104516 2024年10月
  • Wataru Saburi, Haruhide Mori
    Bioscience, Biotechnology, and Biochemistry 88 10 1180 - 1187 2024年07月11日 
    Abstract Starch degradation in malted barley produces yeast-fermentable sugars. In this study, we compared the amylolytic enzymes and composition of the malt starch hydrolysates of two barley cultivars, Hokudai 1 (the first cultivar established in Japan) and Kitanohoshi (the currently used cultivar for beer production). Hokudai 1 malt contained lower activity of amylolytic enzymes than Kitanohoshi malt, although these cultivars contained α-amylase AMY2 and β-amylase Bmy1 as the predominant enzymes. Malt starch hydrolysate of Hokudai 1 contained more limit dextrin and less yeast-fermentable sugars than that of Kitanohoshi. In mixed malt saccharification, a high Hokudai 1 malt ratio increased the limit dextrin levels and decreased the maltotriose and maltose levels. Even though Kitanohoshi malt contained more amylolytic enzymes than Hokudai 1 malt, addition of Kitanohoshi extract containing the amylolytic enzymes did not enhance malt starch degradation of Hokudai 1. Hokudai 1 malt starch was less degradable than Kitanohoshi malt starch.
  • Ryuya Yamamoto, Shigeru Toriumi, Chikara Kawagoe, Wataru Saburi, Hideki Kishimura, Yuya Kumagai
    Bioscience, biotechnology, and biochemistry 2024年04月29日 [査読有り]
     
    Mycosporine-like amino acids (MAAs) are the natural UV absorbing compounds with antioxidant activity found in microalgae and macroalgae. We collected red algae Asparagopsis taxiformis, Meristotheca japonica, and Polysiphonia senticulosa from Nagasaki, where UV radiation is more intense than in Hokkaido, and investigated the effect of UV radiation on MAAs content. It was suggested that A. taxiformis and M. japonica contained shinorine and palythine, while UV absorbing compound in P. senticulosa could not be identified. The amounts of these MAAs were lower compared to those from Hokkaido. Despite an increase in UV radiation in both region from February to April, MAAs contents of red algae from Nagasaki slightly decreased, while that from Hokkaido significantly decreased. This difference was suggested the amount of inorganic nitrogen in the ocean. Antioxidant activity of MAAs increased under alkaline conditions. The extract containing MAAs from P. senticulosa showed the highest antioxidant activity among four red algae.
  • Weeranuch Lang, Takayoshi Tagami, Yuya Kumagai, Seiya Tanaka, Hye-Jin Kang, Masayuki Okuyama, Wataru Saburi, Haruhide Mori, Tohru Hira, Chaehun Lee, Takuya Isono, Toshifumi Satoh, Hiroshi Hara, Takayuki Kurokawa, Nobuo Sakairi, Yoshiaki Yuguchi, Atsuo Kimura
    Carbohydrate Polymers 319 121185 - 121185 2023年11月 [査読有り][通常論文]
  • Tomoya Ota, Wataru Saburi, Takayoshi Tagami, Jian Yu, Shiro Komba, Linda Elizabeth Jewell, Tom Hsiang, Ryozo Imai, Min Yao, Haruhide Mori
    The Journal of biological chemistry 299 11 105294 - 105294 2023年09月27日 [査読有り]
     
    The glycoside hydrolase family 55 (GH55) includes inverting exo-β-1,3-glucosidases and endo-β-1,3-glucanases, acting on laminarin, which is a β1-3/1-6-glucan consisting of a β1-3/1-6-linked main chain and β1-6-linked branches. Despite their different modes of action toward laminarin, endo-β-1,3-glucanases share with exo-β-1,3-glucosidases conserved residues that form the dead-end structure of subsite -1. Here, we investigated the mechanism of endo-type action on laminarin by GH55 endo-β-1,3-glucanase MnLam55A, identified from Microdochium nivale. MnLam55A, like other endo-β-1,3-glucanases, degraded internal β-d-glucosidic linkages of laminarin, producing more reducing sugars than the sum of d-glucose and gentiooligosaccharides detected. β1-3-Glucans lacking β1-6-linkages in the main chain were not hydrolyzed. NMR analysis of the initial degradation of laminarin revealed that MnLam55A preferentially cleaved the non-reducing terminal β1-3-linkage of the laminarioligosaccharide moiety at the reducing end side of the main chain β1-6-linkage. MnLam55A liberates d-glucose from laminaritriose and longer laminarioligosaccharides, but kcat/Km values to laminarioligosaccharides (≤4.21 s-1mM-1) were much lower than to laminarin (5,920 s-1mM-1). These results indicate that β-glucan binding to the minus subsites of MnLam55A, including exclusive binding of the gentiobiosyl moiety to subsites -1 and -2, is required for high hydrolytic activity. A crystal structure of MnLam55A, determined at 2.4 Å resolution, showed that MnLam55A adopts an overall structure and catalytic site similar to those of exo-β-1,3-glucosidases. However, MnLam55A possesses an extended substrate-binding cleft that is expected to form the minus subsites. Sequence comparison suggested that other endo-type enzymes share the extended cleft structure. The specific hydrolysis of internal linkages in laminarin is presumably common to GH55 endo-β-1,3-glucanases.
  • Yusuke Kido, Wataru Saburi, Taizo Nagura, Haruhide Mori
    Bioscience, biotechnology, and biochemistry 87 10 1169 - 1182 2023年09月21日 [査読有り]
     
    Inulin, β-(2→1)-fructan, is a beneficial polysaccharide used as a functional food ingredient. Microbial inulosucrases (ISs), catalyzing β-(2→1)-transfructosylation, produce β-(2→1)-fructan from sucrose. In this study, we identified a new IS (NdIS) from the soil isolate, Neobacillus drentensis 57N. Sequence analysis revealed that, like other Bacillaceae ISs, NdIS consists of a glycoside hydrolase family 68 domain and shares most of the 1-kestose-binding residues of the archaeal IS, InuHj. Native and recombinant NdIS were characterized. NdIS is a homotetramer. It does not require calcium for activity. High performance liquid chromatography and 13C-nuclear magnetic resonance indicated that NdIS catalyzed the hydrolysis and β-(2→1)-transfructosylation of sucrose to synthesize β-(2→1)-fructan with chain lengths of 42 or more residues. The rate dependence on sucrose concentration followed hydrolysis-transglycosylation kinetics, and a 50% transglycosylation ratio was obtained at 344 m m sucrose. These results suggest that transfructosylation from sucrose to β-(2→1)-fructan occurs predominantly to elongate the fructan chain because sucrose is an unfavorable acceptor.
  • Tomoya Ota, Wataru Saburi, Shiro Komba, Haruhide Mori
    Bioscience, biotechnology, and biochemistry 2023年07月05日 [査読有り]
     
    β1-3/1-6 Glucans, known for their diverse structures, comprise a β1-3-linked main chain and β1-6-linked short branches. Laminarin, a β1-3/1-6 glucan extracted from brown seaweed, for instance, includes β1-6 linkages even in the main chain. The diverse structures provide various beneficial functions of the glucan. To investigate the relationship between structure and functionality, and to enable the characterization of β1-3/1-6 glucan-metabolizing enzymes, oligosaccharides containing exact structures of β1-3/1-6 glucans are required. We synthesized the monomeric units for the synthesis of β1-3/1-6 mixed-linked glucooligosaccharides. 2-(Trimethylsilyl)ethyl 2-O-benzoyl-4,6-O-benzylidene-β-d-glucopyranoside served as an acceptor in the formation of β1-3 linkages. Phenyl 2-O-benzoyl-4,6-O-benzylidene-3-O-(tert-butyldiphenylsilyl)-1-thio-β-d-glucopyranoside and phenyl 2,3-di-O-benzoyl-4,6-di-O-levulinyl-1-thio-β-d-glucopyranoside acted as donors, synthesizing acceptors suitable for the formation of β1-3- and β1-6-linkages, respectively. These were used to synthesize a derivative of Glcβ1-6Glcβ1-3Glcβ1-3Glc, demonstrating that the proposed route can be applied to synthesize the main chain of β-glucan, with the inclusion of both β1-3 and β1-6 linkages.
  • Hang Wang, Xiaomei Sun, Wataru Saburi, Saki Hashiguchi, Jian Yu, Toyoyuki Ose, Haruhide Mori, Min Yao
    Acta crystallographica. Section D, Structural biology 79 Pt 7 585 - 595 2023年07月01日 [査読有り]
     
    Mannose 2-epimerase (ME), a member of the acylglucosamine 2-epimerase (AGE) superfamily that catalyzes epimerization of D-mannose and D-glucose, has recently been characterized to have potential for D-mannose production. However, the substrate-recognition and catalytic mechanism of ME remains unknown. In this study, structures of Runella slithyformis ME (RsME) and its D254A mutant [RsME(D254A)] were determined in their apo forms and as intermediate-analog complexes [RsME-D-glucitol and RsME(D254A)-D-glucitol]. RsME possesses the (α/α)6-barrel of the AGE superfamily members but has a unique pocket-covering long loop (loopα7-α8). The RsME-D-glucitol structure showed that loopα7-α8 moves towards D-glucitol and closes the active pocket. Trp251 and Asp254 in loopα7-α8 are only conserved in MEs and interact with D-glucitol. Kinetic analyses of the mutants confirmed the importance of these residues for RsME activity. Moreover, the structures of RsME(D254A) and RsME(D254A)-D-glucitol revealed that Asp254 is vital for binding the ligand in a correct conformation and for active-pocket closure. Docking calculations and structural comparison with other 2-epimerases show that the longer loopα7-α8 in RsME causes steric hindrance upon binding to disaccharides. A detailed substrate-recognition and catalytic mechanism for monosaccharide-specific epimerization in RsME has been proposed.
  • Tomoya Ota, Wataru Saburi, Linda Elizabeth Jewell, Tom Hsiang, Ryozo Imai, Haruhide Mori
    Bioscience, biotechnology, and biochemistry 87 7 707 - 716 2023年06月23日 [査読有り]
     
    Glycoside hydrolase family 3 (GH3) β-glucosidase exists in many filamentous fungi. In phytopathogenic fungi, it is involved in fungal growth and pathogenicity. Microdochium nivale is a severe phytopathogenic fungus of grasses and cereals and is the causal agent of pink snow mold, but its β-glucosidase has not been identified. In this study, a GH3 β-glucosidase of M. nivale (MnBG3A) was identified and characterized. Among various p-nitrophenyl β-glycosides, MnBG3A showed activity on d-glucoside (pNP-Glc) and slight activity on d-xyloside. In the pNP-Glc hydrolysis, substrate inhibition occurred (Kis = 1.6 m m), and d-glucose caused competitive inhibition (Ki = 0.5 m m). MnBG3A acted on β-glucobioses with β1-3, -6, -4, and -2 linkages, in descending order of kcat/Km. In contrast, the regioselectivity for newly formed products was limited to β1-6 linkage. MnBG3A has similar features to those of β-glucosidases from Aspergillus spp., but higher sensitivity to inhibitory effects.
  • Waraporn Auiewiriyanukul, Wataru Saburi, Tomoya Ota, Jian Yu, Koji Kato, Min Yao, Haruhide Mori
    Molecules 28 7 3109 - 3109 2023年03月30日 [査読有り]
     
    α-Glucosidase catalyzes the hydrolysis of α-d-glucosides and transglucosylation. Bacillus sp. AHU2216 α-glucosidase (BspAG13_31A), belonging to the glycoside hydrolase family 13 subfamily 31, specifically cleaves α-(1→4)-glucosidic linkages and shows high disaccharide specificity. We showed previously that the maltose moiety of maltotriose (G3) and maltotetraose (G4), covering subsites +1 and +2 of BspAG13_31A, adopts a less stable conformation than the global minimum energy conformation. This unstable d-glucosyl conformation likely arises from steric hindrance by Asn258 on β→α loop 5 of the catalytic (β/α)8-barrel. In this study, Asn258 mutants of BspAG13_31A were enzymatically and structurally analyzed. N258G/P mutations significantly enhanced trisaccharide specificity. The N258P mutation also enhanced the activity toward sucrose and produced erlose from sucrose through transglucosylation. N258G showed a higher specificity to transglucosylation with p-nitrophenyl α-d-glucopyranoside and maltose than the wild type. E256Q/N258G and E258Q/N258P structures in complex with G3 revealed that the maltose moiety of G3 bound at subsites +1 and +2 adopted a relaxed conformation, whereas a less stable conformation was taken in E256Q. This structural difference suggests that stabilizing the G3 conformation enhances trisaccharide specificity. The E256Q/N258G-G3 complex formed an additional hydrogen bond between Met229 and the d-glucose residue of G3 in subsite +2, and this interaction may enhance transglucosylation.
  • Saburi Wataru, Tomoya Ota, Koji Kato, Takayoshi Tagami, Keitaro Yamashita, Min Yao, Haruhide Mori
    Journal of Applied Glycoscience 70 2 43 - 52 2023年03月11日 
    β-Galactosidase (EC 3.2.1.23) hydrolyzes β-D-galactosidic linkages at the non-reducing end of substrates to produce β-D-galactose. Lacticaseibacillus casei is one of the most widely utilized probiotic species of lactobacilli. It possesses a putative β-galactosidase belonging to glycoside hydrolase family 35 (GH35). This enzyme is encoded by the gene included in the gene cluster for utilization of lacto-N-biose I (LNB; Galβ1-3GlcNAc) and galacto-N-biose (GNB; Galβ1-3GalNAc) via the phosphoenolpyruvate: sugar phosphotransferase system. The GH35 protein (GnbG) from L. casei BL23 is predicted to be 6-phospho-β-galactosidase (EC 3.2.1.85). However, its 6-phospho-β-galactosidase activity has not yet been examined, whereas its hydrolytic activity against LNB and GNB has been demonstrated. In this study, L. casei JCM1134 LBCZ_0230, homologous to GnbG, was characterized enzymatically and structurally. A recombinant LBCZ_0230, produced in Escherichia coli, exhibited high hydrolytic activity toward o-nitrophenyl β-D-galactopyranoside, p-nitrophenyl β-D-galactopyranoside, LNB, and GNB, but not toward o-nitrophenyl 6-phospho-β-D-galactopyranoside. Crystal structure analysis indicates that the structure of subsite -1 of LBCZ_0230 is very similar to that of Streptococcus pneumoniae β-galactosidase BgaC and not suitable for binding to 6-phospho-β-D-galactopyranoside. These biochemical and structural analyses indicate that LBCZ_0230 is a β-galactosidase. According to the prediction of LNB's binding mode, aromatic residues, Trp190, Trp240, Trp243, Phe244, and Tyr458, form hydrophobic interactions with N-acetyl-D-glucosamine residue of LNB at subsite +1.
  • Wataru Saburi, Takanori Nihira, Hiroyuki Nakai, Motomitsu Kitaoka, Haruhide Mori
    Scientific Reports 12 1 2022年12月 [査読有り]
     
    AbstractGlycoside phosphorylases (GPs), which catalyze the reversible phosphorolysis of glycosides, are promising enzymes for the efficient production of glycosides. Various GPs with new catalytic activities are discovered from uncharacterized proteins phylogenetically distant from known enzymes in the past decade. In this study, we characterized Paenibacillus borealis PBOR_28850 protein, belonging to glycoside hydrolase family 94. Screening of acceptor substrates for reverse phosphorolysis, in which α-d-glucose 1-phosphate was used as the donor substrate, revealed that the recombinant PBOR_28850 produced in Escherichia coli specifically utilized d-galactose as an acceptor and produced solabiose (β-d-Glcp-(1 → 3)-d-Gal). This indicates that PBOR_28850 is a new GP, solabiose phosphorylase. PBOR_28850 catalyzed the phosphorolysis and synthesis of solabiose through a sequential bi-bi mechanism involving the formation of a ternary complex. The production of solabiose from lactose and sucrose has been established. Lactose was hydrolyzed to d-galactose and d-glucose by β-galactosidase. Phosphorolysis of sucrose and synthesis of solabiose were then coupled by adding sucrose, sucrose phosphorylase, and PBOR_28850 to the reaction mixture. Using 210 mmol lactose and 280 mmol sucrose, 207 mmol of solabiose was produced. Yeast treatment degraded the remaining monosaccharides and sucrose without reducing solabiose. Solabiose with a purity of 93.7% was obtained without any chromatographic procedures.
  • Naoto Isono, Emi Mizutani, Haruka Hayashida, Hirotaka Katsuzaki, Wataru Saburi
    Biochemical and biophysical research communications 625 60 - 65 2022年10月15日 [査読有り]
     
    Glycoside hydrolase family 94 (GH94) contains enzymes that reversibly catalyze the phosphorolysis of β-glycosides. We conducted this study to investigate a GH94 protein (PBOR_13355) encoded in the genome of Paenibacillus borealis DSM 13188 with low sequence identity to known phosphorylases. Screening of acceptor substrates for reverse phosphorolysis in the presence of α-d-glucose 1-phosphate as a donor substrate showed that PBOR_13355 utilized d-glucuronic acid and p-nitrophenyl β-d-glucuronide as acceptors. In the reaction with d-glucuronic acid, 3-O-β-d-glucopyranosyl-d-glucuronic acid was synthesized. PBOR_13355 showed a higher apparent catalytic efficiency to p-nitrophenyl β-d-glucuronide than to d-glucuronic acid, and thus, PBOR_13355 was concluded to be a novel glycoside phosphorylase, 3-O-β-d-glucopyranosyl β-d-glucuronide phosphorylase. PBOR_13360, encoded by the gene immediately downstream of the PBOR_13355 gene, was shown to be β-glucuronidase. Collectively, PBOR_13355 and PBOR_13360 are predicted to work together in the cytosol to metabolize oligosaccharides containing the 3-O-β-d-glucopyranosyl β-d-glucuronide structure released from bacterial and plant acidic carbohydrates.
  • Yuki Nishida, Wataru Saburi, Yoshikatsu Miyabe, Hideki Kishimura, Yuya Kumagai
    Marine drugs 20 3 2022年03月01日 [査読有り]
     
    We recently demonstrated the monthly variation and antioxidant activity of mycosporine-like amino acids (MAAs) from red alga dulse in Japan. The antioxidant activity of MAAs in acidic conditions was low compared to that in neutral and alkali conditions, but we found strong antioxidant activity from the heated crude MAA fraction in acidic conditions. In this study, we identified and characterized the key compounds involved in the antioxidant activity of this fraction. We first isolated two MAAs, palythine, and porphyra-334, from the fraction and evaluated the activities of the two MAAs when heated. MAAs possess absorption maxima at around 330 nm, while the heated MAAs lost this absorption. The heated MAAs showed a high ABTS radical scavenging activity at pH 5.8-8.0. We then determined the structure of heated palythine via ESI-MS and NMR analyses and speculated about the putative antioxidant mechanism. Finally, a suitable production condition of the heated compounds was determined at 120 °C for 30 min at pH 8.0. We revealed compounds from red algae with antioxidant activities at a wide range of pH values, and this information will be useful for the functional processing of food.
  • Shu Horikoshi, Wataru Saburi, Jian Yu, Hideyuki Matsuura, James R Ketudat Cairns, Min Yao, Haruhide Mori
    Bioscience, biotechnology, and biochemistry 86 2 231 - 245 2022年01月24日 [査読有り]
     
    Plants possess many glycoside hydrolase family 1 (GH1) β-glucosidases, which physiologically function in cell wall metabolism and activation of bioactive substances, but most remain uncharacterized. One GH1 isoenzyme AtBGlu42 in Arabidopsis thaliana has been identified to hydrolyze scopolin using the gene deficient plants, but no enzymatic properties were obtained. Its sequence similarity to another functionally characterized enzyme Os1BGlu4 in rice suggests that AtBGlu42 also acts on oligosaccharides. Here, we show that the recombinant AtBGlu42 possesses high kcat/Km not only on scopolin, but also on various β-glucosides, cellooligosaccharides, and laminarioligosaccharides. Of the cellooligosaccharides, cellotriose was the most preferred. The crystal structure, determined at 1.7 Å resolution, suggests that Arg342 gives unfavorable binding to cellooligosaccharides at subsite +3. The mutants R342Y and R342A showed the highest preference on cellotetraose or cellopentaose with increased affinities at subsite +3, indicating that the residues at this position have an important role for chain length specificity.
  • Weeranuch Lang, Yuya Kumagai, Juri Sadahiro, Wataru Saburi, Rakrudee Sarnthima, Takayoshi Tagami, Masayuki Okuyama, Haruhide Mori, Nobuo Sakairi, Doman Kim, Atsuo Kimura
    Applied microbiology and biotechnology 106 2 689 - 698 2022年01月 [査読有り]
     
    Dextran dextrinase (DDase) catalyzes formation of the polysaccharide dextran from maltodextrin. During the synthesis of dextran, DDase also generates the beneficial material isomaltomegalosaccharide (IMS). The term megalosaccharide is used for a saccharide having DP = 10-100 or 10-200 (DP, degree of polymerization). IMS is a chimeric glucosaccharide comprising α-(1 → 6)- and α-(1 → 4)-linked portions at the nonreducing and reducing ends, respectively, in which the α-(1 → 4)-glucosyl portion originates from maltodextrin of the substrate. In this study, IMS was produced by a practical approach using extracellular DDase (DDext) or cell surface DDase (DDsur) of Gluconobacter oxydans ATCC 11894. DDsur was the original form, so we prepared DDext via secretion from intact cells by incubating with 0.5% G6/G7 (maltohexaose/maltoheptaose); this was followed by generation of IMS from various concentrations of G6/G7 substrate at different temperatures for 96 h. However, IMS synthesis by DDext was limited by insufficient formation of α-(1 → 6)-glucosidic linkages, suggesting that DDase also catalyzes elongation of α-(1 → 4)-glucosyl chain. For production of IMS using DDsur, intact cells bearing DDsur were directly incubated with 20% G6/G7 at 45 °C by optimizing conditions such as cell concentration and agitation efficiency, which resulted in generation of IMS (average DP = 14.7) with 61% α-(1 → 6)-glucosyl content in 51% yield. Increases in substrate concentration and agitation efficiency were found to decrease dextran formation and increase IMS production, which improved the reaction conditions for DDext. Under modified conditions (20% G6/G7, agitation speed of 100 rpm at 45 °C), DDext produced IMS (average DP = 14.5) with 65% α-(1 → 6)-glucosyl content in a good yield of 87%. KEY POINTS: • Beneficial IMS was produced using thermostabilized DDase. • Optimum conditions for reduced dextran formation were successfully determined. • A practical approach was established to provide IMS with a great yield of 87%.
  • Daisuke Tezuka, Hideyuki Matsuura, Wataru Saburi, Haruhide Mori, Ryozo Imai
    Plants (Basel, Switzerland) 10 9 2021年09月10日 [査読有り]
     
    Salicylic acid (SA) is a phytohormone that regulates a variety of physiological and developmental processes, including disease resistance. SA is a key signaling component in the immune response of many plant species. However, the mechanism underlying SA-mediated immunity is obscure in rice (Oryza sativa). Prior analysis revealed a correlation between basal SA level and blast resistance in a range of rice varieties. This suggested that resistance might be improved by increasing basal SA level. Here, we identified a novel UDP-glucosyltransferase gene, UGT74J1, which is expressed ubiquitously throughout plant development. Mutants of UGT74J1 generated by genome editing accumulated high levels of SA under non-stressed conditions, indicating that UGT74J1 is a key enzyme for SA homeostasis in rice. Microarray analysis revealed that the ugt74j1 mutants constitutively overexpressed a set of pathogenesis-related (PR) genes. An inoculation assay demonstrated that these mutants had increased resistance against rice blast, but they also exhibited stunted growth phenotypes. To our knowledge, this is the first report of a rice mutant displaying SA overaccumulation.
  • Ting-Yu Cheng, Yen-Ju Lin, Wataru Saburi, Stefan Vieths, Stephan Scheurer, Stefan Schülke, Masako Toda
    Cells 10 7 2021年07月14日 [査読有り]
     
    Some β-mannans, including those in coffee bean and soy, contain a mannose backbone with β-(1→4) bonds. Such mannooligosaccharides could have immunological functions involving direct interaction with immune cells, in addition to acting as prebiotics. This study aimed at assessing the immunological function of mannooligosaccharides with β-(1→4) bond, and elucidating their mechanism of action using bone marrow-derived murine dendritic cells (BMDCs). When BMDCs were stimulated with the mannooligosaccharides, only β-Man-(1→4)-Man significantly induced production of cytokines that included IL-6, IL-10, TNF-α, and IFN-β, and enhanced CD4+ T-cell stimulatory capacity. Use of putative receptor inhibitors revealed the binding of β-Man-(1→4)-Man to TLR4/MD2 complex and involvement with the complement C3a receptor (C3aR) for BMDC activation. Interestingly, β-Man-(1→4)-Man prolonged the production of pro-inflammatory cytokines (IL-6 and TNF-α), but not of the IL-10 anti-inflammatory cytokine during extended culture of BMDCs, associated with high glucose consumption. The results suggest that β-Man-(1→4)-Man is an immunostimulatory molecule, and that the promotion of glycolysis could be involved in the production of pro-inflammatory cytokine in β-Man-(1→4)-Man-stimulated BMDCs. This study could contribute to development of immune-boosting functional foods and a novel vaccine adjuvant.
  • Chikako Kuwabara, Kentaro Sasaki, Natsuki Umeki, Tamotsu Hoshino, Wataru Saburi, Hirokazu Matsui, Ryozo Imai
    Plant physiology 185 4 1489 - 1494 2021年02月02日 [査読有り]
  • Kensuke Fukui, Wataru Saburi, Masahisa Ibuki, Kazunobu Tsumura, Haruhide Mori
    Food Science and Technology Research 27 2 249 - 257 2021年 [査読有り]
  • Yodai Taguchi, Wataru Saburi, Ryozo Imai, Haruhide Mori
    Carbohydrate research 488 107902 - 107902 2020年02月 [査読有り][通常論文]
     
    Trehalose 6-phosphate (Tre6P) is an important intermediate for trehalose biosynthesis. Recent researches have revealed that Tre6P is an endogenous signaling molecule that regulates plant development and stress responses. The necessity of Tre6P in physiological studies is expected to be increasing. To achieve the cost-effective production of Tre6P, a novel approach is required. In this study, we utilized trehalose 6-phosphate phosphorylase (TrePP) from Lactococcus lactis to produce Tre6P. In the reverse phosphorolysis by the TrePP, 91.9 mM Tre6P was produced from 100 mM β-glucose 1-phosphate (β-Glc1P) and 100 mM glucose 6-phosphate (Glc6P). The one-pot reaction of TrePP and maltose phosphorylase (MP) enabled production of 65 mM Tre6P from 100 mM maltose, 100 mM Glc6P, and 20 mM inorganic phosphate. Addition of β-phosphoglucomutase to this reaction produced Glc6P from β-Glc1P and thus reduced requirement of Glc6P as a starting material. Within the range of 20-469 mM inorganic phosphate tested, the 54 mM concentration yielded the highest amount of Tre6P (33 mM). Addition of yeast increased the yield because of its glucose consumption. Finally, from 100 mmol maltose and 60 mmol inorganic phosphate, we successfully achieved production of 37.5 mmol Tre6P in a one-pot reaction (100 mL), and 9.4 g Tre6P dipotassium salt was obtained.
  • M Ejby, A Guskov, M J Pichler, G C Zanten, E Schoof, W Saburi, D J Slotboom, M Abou Hachem
    Molecular microbiology 112 1 114 - 130 2019年07月 [査読有り]
     
    Human gut bifidobacteria rely on ATP-binding cassette (ABC) transporters for oligosaccharide uptake. Multiple oligosaccharide-specific solute-binding protein (SBP) genes are occasionally associated with a single ABC transporter, but the significance of this multiplicity remains unclear. Here, we characterize BlMnBP1 and BlMnBP2, the two SBPs associated to the β-manno-oligosaccharide (MnOS) ABC transporter in Bifidobacterium animalis subsp. lactis. Despite similar overall specificity and preference to mannotriose (Kd ≈80 nM), affinity of BlMnBP1 is up to 2570-fold higher for disaccharides than BlMnBP2. Structural analysis revealed a substitution of an asparagine that recognizes the mannosyl at position 2 in BlMnBP1, by a glycine in BlMnBP2, which affects substrate affinity. Both substitution types occur in bifidobacterial SBPs, but BlMnBP1-like variants prevail in human gut isolates. B. animalis subsp. lactis ATCC27673 showed growth on gluco and galactomannans and was able to outcompete a mannan-degrading Bacteroides ovatus strain in co-cultures, attesting the efficiency of this ABC uptake system. By contrast, a strain that lacks this transporter failed to grow on mannan. This study highlights SBP diversification as a possible strategy to modulate oligosaccharide uptake preferences of bifidobacterial ABC-transporters during adaptation to specific ecological niches. Efficient metabolism of galactomannan by distinct bifidobacteria, merits evaluating this plant glycan as a potential prebiotic.
  • Gao Y, Saburi W, Taguchi Y, Mori H
    Bioscience, biotechnology, and biochemistry 83 2097 - 2109 2019年07月 [査読有り][通常論文]
  • Saburi W, Sato S, Hashiguchi S, Muto H, Iizuka T, Mori H
    Applied microbiology and biotechnology 2019年06月 [査読有り][通常論文]
  • Y.Yamamoto, H.Kishimura, Y.Kinoshita, W.Saburi, Y.Kumagai, H.Yasui, T.Ojima
    Process Biochemistry 2019年04月 [査読有り][通常論文]
  • Tezuka D, Kawamata A, Kato H, Saburi W, Mori H, Imai R
    Plant physiology and biochemistry : PPB 135 263 - 271 2019年02月 [査読有り][通常論文]
  • Myint H, Kishi H, Iwahashi Y, Saburi W, Koike S, Kobayashi Y
    Beneficial microbes 9 6 1 - 12 2018年09月 [査読有り][通常論文]
     
    A feeding study using rats was conducted to evaluate the utility of lablab bean husk and soya bean husk as sources of potential prebiotic fibre. Twenty 5-week-old Sprague Dawley rats were divided into 4 groups and fed one of the following diets for 3 weeks: purified diet (AIN93 G) containing 5% cellulose (CEL), or the same diet in which cellulose was replaced by corn starch (STA), lablab bean husk (LBH), or soya bean husk (SBH). Rats were sacrificed at 8 weeks of age and caecal digesta were collected. Feed intake, body weight, anatomical parameters, and caecal ammonia level did not differ significantly among diets. Rats on LBH and SBH showed higher concentrations of caecal short-chain fatty acid and lactate than those on CEL. Rats on CEL, SBH, and LBH exhibited lower caecal indole and skatole levels. LBH yielded increased caecal abundance of Akkermansia muciniphila and Oscillibacter relatives, as demonstrated by either qPCR, MiSeq, or clone library analysis. SBH favoured the growth of lactobacilli as assessed by both qPCR and MiSeq, and favoured the growth of bifidobacteria as assessed by MiSeq. In comparison with STA, LBH and SBH yielded lower caecal abundance of bacteria related to Dorea massiliensis, as demonstrated by qPCR, MiSeq, and clone library analysis. Both types of bean husk were found to contain oligosaccharides that might selectively stimulate the growth of beneficial bacteria. Based on these results, the two species of bean husk tested are considered potentially functional for promoting the gut health of monogastric animals.
  • Mikiyasu Sakanaka, Shingo Nakakawaji, Shin Nakajima, Satoru Fukiya, Arisa Abe, Wataru Saburi, Haruhide Mori, Atsushi Yokota
    Applied and environmental microbiology 84 17 2018年09月01日 [査読有り][通常論文]
     
    Bifidobacteria are a major component of the intestinal microbiota in humans, particularly breast-fed infants. Therefore, elucidation of the mechanisms by which these bacteria colonize the intestine is desired. One approach is transposon mutagenesis, a technique currently attracting much attention because, in combination with next-generation sequencing, it enables exhaustive identification of genes that contribute to microbial fitness. We now describe a transposon mutagenesis system for Bifidobacterium longum subsp. longum 105-A (JCM 31944) based on ISBlo11, a native IS3 family insertion sequence. To build this system, xylose-inducible or constitutive bifidobacterial promoters were tested to drive the expression of full-length or a truncated form at the N terminus of the ISBlo11 transposase. An artificial transposon plasmid, pBFS12, in which ISBlo11 terminal inverted repeats are separated by a 3-bp spacer, was also constructed to mimic the transposition intermediate of IS3 elements. The introduction of this plasmid into a strain expressing transposase resulted in the insertion of the plasmid with an efficiency of >103 CFU/μg DNA. The plasmid targets random 3- to 4-bp sequences, but with a preference for noncoding regions. This mutagenesis system also worked at least in B. longum NCC2705. Characterization of a transposon insertion mutant revealed that a putative α-glucosidase mediates palatinose and trehalose assimilation, demonstrating the suitability of transposon mutagenesis for loss-of-function analysis. We anticipate that this approach will accelerate functional genomic studies of B. longum subsp. longumIMPORTANCE Several hundred species of bacteria colonize the mammalian intestine. However, the genes that enable such bacteria to colonize and thrive in the intestine remain largely unexplored. Transposon mutagenesis, combined with next-generation sequencing, is a promising tool to comprehensively identify these genes but has so far been applied only to a small number of intestinal bacterial species. In this study, a transposon mutagenesis system was established for Bifidobacterium longum subsp. longum, a representative health-promoting Bifidobacterium species. The system enables the identification of genes that promote colonization and survival in the intestine and should help illuminate the physiology of this species.
  • Auiewiriyanukul W, Saburi W, Kato K, Yao M, Mori H
    FEBS letters 592 13 2268 - 2281 2018年07月 [査読有り][通常論文]
  • Wataru Saburi, Nongluck Jaito, Koji Kato, Yuka Tanaka, Min Yao, Haruhide Mori
    Biochimie 144 63 - 73 2018年01月01日 [査読有り][通常論文]
     
    D-Mannose isomerase (MI) reversibly isomerizes D-mannose to D-fructose, and is attractive for producing D-mannose from inexpensive D-fructose. It belongs to the N-acylglucosamine 2-epimerase (AGE) superfamily along with AGE, cellobiose 2-epimerase (CE), and aldose-ketose isomerase (AKI). In this study, Marinomonas mediterranea Marme_2490, showing low sequence identity with any known enzymes, was found to isomerize D-mannose as its primary substrate. Marme_2490 also isomerized D-lyxose and 4-OH D-mannose derivatives (D-talose and 4-O-monosaccharyl-D-mannose). Its activity for D-lyxose is known in other D-mannose isomerizing enzymes, such as MI and AKI, but we identified, for the first time, its activity for 4-OH D-mannose derivatives. Marme_2490 did not isomerize D-glucose, as known MIs do not, while AKI isomerizes both D-mannose and D-glucose. Thus, Marme_2490 was concluded to be an MI. The initial and equilibrium reaction products were analyzed by NMR to illuminate mechanistic information regarding the Marme_2490 reaction. The analysis of the initial reaction product revealed that β-D-mannose was formed. In the analysis of the equilibrated reaction products in D2O, signals of 2-H of D-mannose and 1-H of D-fructose were clearly detected. This indicates that these protons are not substituted with deuterium from D2O and Marme_2490 catalyzes the intramolecular proton transfer between 1-C and 2-C. The crystal structure of Marme_2490 in a ligand-free form was determined and found that Marme_2490 is formed by an (α/α)6-barrel, which is commonly observed in AGE superfamily enzymes. Despite diverse reaction specificities, the orientations of residues involved in catalysis and substrate binding by Marme_2490 were similar to those in both AKI (Salmonella enterica AKI) and epimerase (Rhodothermus marinus CE). The Marme_2490 structure suggested that the α7→α8 and α11→α12 loops of the catalytic domain participated in the formation of an open substrate-binding site to provide sufficient space to bind 4-OH D-mannose derivatives.
  • Ryo Matsui, Naruki Amano, Kosaku Takahashi, Yodai Taguchi, Wataru Saburi, Hideharu Mori, Norio Kondo, Kazuhiko Matsuda, Hideyuki Matsuura
    SCIENTIFIC REPORTS 7 1 6688  2017年07月 [査読有り][通常論文]
     
    In plants, cis-jasmone (CJ) is synthesized from a-linolenic acid (LA) via two biosynthetic pathways using jasmonic acid (JA) and iso-12-oxo-phytodienoic acid (iso-OPDA) as key intermediates. However, there have been no reports documenting CJ production by microorganisms. In the present study, the production of fungal-derived CJ by Lasiodiplodia theobromae was observed for the first time, although this production was not observed for Botrytis cinerea, Verticillium longisporum, Fusarium oxysporum, Gibberella fujikuroi, and Cochliobolus heterostrophus. To investigate the biosynthetic pathway of CJ in L. theobromae, administration experiments using [18,18,18-H-2(3), 17,17-H-2(2)] LA (LA-d5), [18,18,18-H-2(3), 17,17-H-2(2)]12-oxo-phytodienoic acid (cis-OPDA-d5), [5', 5', 5'-H-2(3), 4', 4'-H-2(2), 3'-H-2(1)] OPC 8:0 (OPC8-d6), [5', 5', 5'-H-2(3), 4', 4'-H-2(2), 3'-H-2(1)] OPC 6:0 (OPC6-d6), [5', 5', 5'-H-2(3), 4', 4'-H-2(2), 3'-H-2(1)] OPC 4:0 (OPC4-d6), and [11,11-H-2(2), 10,10-H-2(2), 8,8-H-2(2), 2,2-H-2(2)] methyl iso-12-oxo-phytodienoate (iso-MeOPDA-d8) were carried out, revealing that the fungus produced CJ through a single biosynthetic pathway via iso-OPDA. Interestingly, it was suggested that the previously predicted decarboxylation step of 3,7-didehydroJA to afford CJ might not be involved in CJ biosynthesis in L. theobromae.
  • Yodai Taguchi, Wataru Saburi, Ryozo Imai, Haruhide Mori
    BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY 81 8 1512 - 1519 2017年 [査読有り][通常論文]
     
    Trehalose 6-phosphate phosphorylase (TrePP), a member of glycoside hydrolase family 65, catalyzes the reversible phosphorolysis of trehalose 6-phosphate (Tre6P) with inversion of the anomeric configuration to produce beta-D-glucose 1-phosphate (beta-Glc1P) and D-glucose 6-phosphate (Glc6P). TrePP in Lactococcus lactis ssp. lactis (LlTrePP) is, alongside the phosphotransferase system, involved in the metabolism of trehalose. In this study, recombinant LlTrePP was produced and characterized. It showed its highest reverse phosphorolytic activity at pH 4.8 and 40 degrees C, and was stable in the pH range 5.0-8.0 and at up to 30 degrees C. Kinetic analyses indicated that reverse phosphorolysis of Tre6P proceeded through a sequential bi bi mechanism involving the formation of a ternary complex of the enzyme, beta-Glc1P, and Glc6P. Suitable acceptor substrates were Glc6P, and, at a low level, D-mannose 6-phosphate (Man6P). From beta-Glc1P and Man6P, a novel sugar phosphate, alpha-D-Glcp-(1 <-> 1)-alpha-D-Manp6P, was synthesized with 51% yield.
  • Wataru Saburi
    BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY 80 7 1294 - 1305 2016年07月 [査読有り][通常論文]
     
    Carbohydrate isomerases/epimerases are essential in carbohydrate metabolism, and have great potential in industrial carbohydrate conversion. Cellobiose 2-epimerase (CE) reversibly epimerizes the reducing end d-glucose residue of -(14)-linked disaccharides to d-mannose residue. CE shares catalytic machinery with monosaccharide isomerases and epimerases having an (/)(6)-barrel catalytic domain. Two histidine residues act as general acid and base catalysts in the proton abstraction and addition mechanism. -Mannoside hydrolase and 4-O--d-mannosyl-d-glucose phosphorylase (MGP) were found as neighboring genes of CE, meaning that CE is involved in -mannan metabolism, where it epimerizes -d-mannopyranosyl-(14)-d-mannose to -d-mannopyranosyl-(14)-d-glucose for further phosphorolysis. MGPs form glycoside hydrolase family 130 (GH130) together with other -mannoside phosphorylases and hydrolases. Structural analysis of GH130 enzymes revealed an unusual catalytic mechanism involving a proton relay and the molecular basis for substrate and reaction specificities. Epilactose, efficiently produced from lactose using CE, has superior physiological functions as a prebiotic oligosaccharide.
  • Okuyama M, Saburi W, Mori H, Kimura A
    Cellular and molecular life sciences : CMLS 73 14 2727 - 2751 2016年07月 [査読有り][通常論文]
     
    alpha-Glucosidases (AGases) and alpha-1,4-glucan lyases (GLases) catalyze the degradation of alpha-glucosidic linkages at the non-reducing ends of substrates to release alpha-glucose and anhydrofructose, respectively. The AGases belong to glycoside hydrolase (GH) families 13 and 31, and the GLases belong to GH31 and share the same structural fold with GH31 AGases. GH13 and GH31 AGases show diverse functions upon the hydrolysis of substrates, having linkage specificities and size preferences, as well as upon transglucosylation, forming specific alpha-glucosidic linkages. The crystal structures of both enzymes were determined using free and ligand-bound forms, which enabled us to understand the important structural elements responsible for the diverse functions. A series of mutational approaches revealed features of the structural elements. In particular, amino-acid residues in plus subsites are of significance, because they regulate transglucosylation, which is used in the production of industrially valuable oligosaccharides. The recently solved three-dimensional structure of GLase from red seaweed revealed the amino-acid residues essential for lyase activity and the strict recognition of the alpha-(1 -> 4)-glucosidic substrate linkage. The former was introduced to the GH31 AGase, and the resultant mutant displayed GLase activity. GH13 and GH31 AGases hydrate anhydrofructose to produce glucose, suggesting that AGases are involved in the catabolic pathway used to salvage unutilized anhydrofructose.
  • Kentaro Sasaki, Chikako Kuwabara, Natsuki Umeki, Mari Fujioka, Wataru Saburi, Hirokazu Matsui, Fumitaka Abe, Ryozo Imai
    JOURNAL OF BIOTECHNOLOGY 228 3 - 7 2016年06月 [査読有り][通常論文]
     
    TAD1 (Triticum aestivum defensin 1) is induced during cold acclimation in winter wheat and encodes a plant defensin with antimicrobial activity. In this study, we demonstrated that recombinant TAD1 protein inhibits hyphal growth of the snow mold fungus, Typhula ishikariensis in vitro. Transgenic wheat plants overexpressing TAD1 were created and tested for resistance against T. ishikariensis. Leaf inoculation assays revealed that overexpression of TAD1 confers resistance against the snow mold. In addition, the TAD1-overexpressors showed resistance against Fusarium graminearum, which causes Fusarium head blight, a devastating disease in wheat and barley. These results indicate that TAD1 is a candidate gene to improve resistance against multiple fungal diseases in cereal crops. (C) 2016 Elsevier B.V. All rights reserved.
  • Masuda Y, Okuyama M, Iizuka T, Nakai H, Saburi W, Fukukawa T, Maneesan J, Tagami T, Naraoka T, Mori H, Kimura A
    Bioscience, biotechnology, and biochemistry 80 3 479 - 485 2016年03月 [査読有り][通常論文]
     
    Marine glycoside hydrolases hold enormous potential due to their habitat-related characteristics such as salt tolerance, barophilicity, and cold tolerance. We purified an -glucosidase (PYG) from the midgut gland of the Japanese scallop (Patinopecten yessoensis) and found that this enzyme has unique characteristics. The use of acarbose affinity chromatography during the purification was particularly effective, increasing the specific activity 570-fold. PYG is an interesting chloride ion-dependent enzyme. Chloride ion causes distinctive changes in its enzymatic properties, increasing its hydrolysis rate, changing the pH profile of its enzyme activity, shifting the range of its pH stability to the alkaline region, and raising its optimal temperature from 37 to 55 degrees C. Furthermore, chloride ion altered PYG's substrate specificity. PYG exhibited the highest V-max/K-m value toward maltooctaose in the absence of chloride ion and toward maltotriose in the presence of chloride ion.
  • Yuxin Ye, Wataru Saburi, Rei Odaka, Koji Kato, Naofumi Sakurai, Keisuke Komoda, Mamoru Nishimoto, Motomitsu Kitaoka, Haruhide Mori, Min Yao
    FEBS LETTERS 590 6 828 - 837 2016年03月 [査読有り][通常論文]
     
    In Ruminococcus albus, 4-Omicron-beta-D-mannosyl-D-glucose phosphorylase (RaMP1) and beta-(1,4)-mannooligosaccharide phosphorylase (RaMP2) belong to two subfamilies of glycoside hydrolase family 130. The two enzymes phosphorolyze beta-mannosidic linkages at the nonreducing ends of their substrates, and have substantially diverse substrate specificity. The differences in their mechanism of substrate binding have not yet been fully clarified. In the present study, we report the crystal structures of RaMP1 with/without 4-Omicron-beta-D-mannosyl-D-glucose and RaMP2 with/without beta-(1 -> 4)-mannobiose. The structures of the two enzymes differ at the +1 subsite of the substrate-binding pocket. Three loops are proposed to determine the different substrate specificities. One of these loops is contributed from the adjacent molecule of the oligomer structure. In RaMP1, His245 of loop 3 forms a hydrogen-bond network with the substrate through a water molecule, and is indispensible for substrate binding.
  • Yuki Murakami, Teruyo Ojima-Kato, Wataru Saburi, Haruhide Mori, Hirokazu Matsui, Soichi Tanabe, Takuya Suzuki
    BRITISH JOURNAL OF NUTRITION 114 11 1774 - 1783 2015年12月 [査読有り][通常論文]
     
    Obesity is one of the major health problems throughout the world. The present study investigated the preventive effect of epilactose - a rare non-digestible disaccharide - on obesity and metabolic disorders in mice fed high-fat (HF) diets. Feeding with HF diets increased body weight gain, fat pad weight and adipocyte size in mice (P<0.01), and these increases were effectively prevented by the use of supplemental epilactose without influencing food intake (P<0.01). Caecal pools of SCFA such as acetic and propionic acids in mice fed epilactose were higher compared with mice not receiving epilactose. Supplemental epilactose increased the expression of uncoupling protein (UCP)-1, which enhances energy expenditure, to 2-fold in the gastrocnemius muscle (P=0.04) and to 1.3-fold in the brown adipose tissue (P=0.02) in mice fed HF diets. Feeding HF diets induced pro-inflammatory macrophage infiltration into white adipose tissue, as indicated by the increased expression of monocyte chemotactic protein-1, TNF-alpha and F4/80, and these increases were attenuated by supplemental epilactose. In differentiated myogenic-like C2C12 cells, propionic acid, but not acetic or n-butyric acids, directly enhanced UCP-1 expression by approximately 2-fold (P<0.01). Taken together, these findings indicate that the epilactose-mediated increase in UCP-1 in the skeletal muscle and brown adipose tissue can enhance whole-body energy expenditure, leading to effective prevention of obesity and metabolic disorders in mice fed HF diets. It is suggested that propionic acid - a bacterial metabolite - acts as a mediator to induce UCP-1 expression in skeletal muscles.
  • Hua Y, Ekkhara W, Sansenya S, Srisomsap C, Roytrakul S, Saburi W, Takeda R, Matsuura H, Mori H, Ketudat Cairns JR
    Archives of biochemistry and biophysics 583 36 - 46 2015年10月 [査読有り][通常論文]
     
    Gibberellin 1-O-beta-D-glucose ester hydrolysis activity has been detected in rice seedling extracts, but no enzyme responsible for this activity has ever been purified and identified. Therefore, gibberellin A4 glucosyl ester (GA(4)-GE) beta-D-glucosidase activity was purified from ten-day rice seedling stems and leaves. The family 1 glycoside hydrolase Os4BGlu13 was identified in the final purification fraction. The Os4BGlu13 cDNA was amplified from rice seedlings and expressed as an N-terminal thioredoxin-tagged fusion protein in Escherichia coll. The purified recombinant Os4BGlu13 protein (rOs4BGlu13) had an optimum pH of 4.5, for hydrolysis of p-nitrophenyl beta-D-glucopyranoside (pNPGlc), which was the best substrate identified, with a k(cat)/K-m of 637 mM(-1) s(-1). rOs4BGlu13 hydrolyzed helicin best among natural glycosides tested (K-cat/K-m, of 74.4 mM(-1) s(-1)). Os4BGlu13 was previously designated tuberonic acid glucoside (TAG) beta-glucosidase (TAGG), and here the k(cat)/K-m of rOsBGlu13 for TAG was 6.68 mM(-1) s(-1), while that for GA4-GE was 3.63 mM(-1) s(-1) and for salicylic acid glucoside (SAG) is 0.88 mM(-1) s(-1). rOs4BGlu13 also hydrolyzed oligosaccharides, with preference for short beta-(1 -> 3)-linked over beta-(1 -> 4)linked glucooligosaccharides. The enzymatic data suggests that Os4BGlu13 may contribute to TAG, SAG, oligosaccharide and GA4-GE hydrolysis in the rice plant, although helicin or a similar compound may be its primary target. (C) 2015 Elsevier Inc. All rights reserved.
  • Saburi W, Tanaka Y, Muto H, Inoue S, Odaka R, Nishimoto M, Kitaoka M, Mori H
    Bioscience, biotechnology, and biochemistry 79 6 969 - 977 2015年06月 [査読有り][通常論文]
     
    The aerobic soil bacterium Cellvibrio vulgaris has a beta-mannan-degradation gene cluster, including unkA, epiA, man5A, and aga27A. Among these genes, epiA has been assigned to encode an epimerase for converting d-mannose to d-glucose, even though the amino acid sequence of EpiA is similar to that of cellobiose 2-epimerases (CEs). UnkA, whose function currently remains unknown, shows a high sequence identity to 4-O-beta-d-mannosyl-d-glucose phosphorylase. In this study, we have investigated CE activity of EpiA and the general characteristics of UnkA using recombinant proteins from Escherichia coli. Recombinant EpiA catalyzed the epimerization of the 2-OH group of sugar residue at the reducing end of cellobiose, lactose, and beta-(1 -> 4)-mannobiose in a similar manner to other CEs. Furthermore, the reaction efficiency of EpiA for beta-(1 -> 4)-mannobiose was 5.5x10(4)-fold higher than it was for d-mannose. Recombinant UnkA phosphorolyzed beta-d-mannosyl-(1 -> 4)-d-glucose and specifically utilized d-glucose as an acceptor in the reverse reaction, which indicated that UnkA is a typical 4-O-beta-d-mannosyl-d-glucose phosphorylase.
  • Wataru Saburi, Hiroaki Rachi-Otsuka, Hironori Hondoh, Masayuki Okuyama, Haruhide Mori, Atsuo Kimura
    FEBS LETTERS 589 7 865 - 869 2015年03月 [査読有り][通常論文]
     
    Glycoside hydrolase family 13 contains exo-glucosidases specific for alpha-(1 -> 4)- and alpha-(1 -> 6)-linkages including alpha-glucosidase, oligo-1,6-glucosidase, and dextran glucosidase. The alpha-(1 -> 6)-linkage selectivity of Streptococcus mutans dextran glucosidase was altered to alpha-(1 -> 4)-linkage selectivity through site-directed mutations at Val195, Lys275, and Glu371. V195A showed 1300-fold higher k(cat)/K-m for maltose than wild-type, but its k(cat)/K-m for isomaltose remained 2-fold higher than for maltose. K275A and E371A combined with V195A mutation only decreased isomaltase activity. V195A/K275A, V195A/E371A, and V195A/K275A/E371A showed 27-, 26-, and 73-fold higher k(cat)/K-m for maltose than for isomaltose, respectively. Consequently, the three residues are structural elements for recognition of the alpha-(1 -> 6)-glucosidic linkage. (C) 2015 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.
  • Momoko Kobayashi, Wataru Saburi, Daichi Nakatsuka, Hironori Hondoh, Koji Kato, Masayuki Okuyama, Haruhide Mori, Atsuo Kimura, Min Yao
    FEBS LETTERS 589 4 484 - 489 2015年02月 [査読有り][通常論文]
     
    Streptococcus mutans dextran glucosidase (SmDG) belongs to glycoside hydrolase family 13, and catalyzes both the hydrolysis of substrates such as isomaltooligosaccharides and subsequent transglucosylation to form alpha-(1 -> 6)-glucosidic linkage at the substrate non-reducing ends. Here, we report the 2.4 angstrom resolution crystal structure of glucosyl-enzyme intermediate of SmDG. In the obtained structure, the Trp238 side-chain that constitutes the substrate-binding site turned away from the active pocket, concurrently with conformational changes of the nucleophile and the acid/base residues. Different conformations of Trp238 in each reaction stage indicated its flexibility. Considering the results of kinetic analyses, such flexibility may reflect a requirement for the reaction mechanism of SmDG. (C) 2015 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.
  • Sadahiro J, Mori H, Saburi W, Okuyama M, Kimura A
    Biochem Biophys Res Commun 456 1 500 - 505 2015年 [査読有り][通常論文]
     
    Gluconobacter oxydans ATCC 11894 produces dextran dextrinase (DDase, EC 2.4.1.2), which synthesizes dextran from the starch hydrolysate, dextrin and is known to cause ropy beer. G. oxydans ATCC 11894 was believed to possess both a secreted DDase (DDext) and an intracellular DDase (DDint), expressed upon cultivation with dextrin and glucose, respectively. However, genomic Southern blot, peptide mass fingerprinting and reaction product-pattern analyses revealed that both DDext and DDint were identical. The activity in the cell suspension and its liberation from the spheroplast cells indicated that DDint was localized on the cell surface. The localization of DDase was altered during the culture depending on the growth phase. During the early growth stage, DDase was exclusively liberated into the medium (DDext), and the cell-associated form (DDint) appeared after depletion of glucose from the medium. (C) 2014 Elsevier Inc. All rights reserved.
  • Saburi W, Okuyama M, Kumagai Y, Kimura A, Mori H
    Biochimie 108 108 140 - 148 Elsevier 2015年 [査読有り][通常論文]
     
    α-Glucosidases are ubiquitous enzymes that hydrolyze the α-glucosidic linkage at the non-reducing end of substrates. In this study, we characterized an α-glucosidase (BspAG31A) belonging to glycoside hydrolase family 31 from Bacillus sp. AHU 2001. Recombinant BspAG31A, produced in Escherichia coli, had high hydrolytic activity toward maltooligosaccharides, kojibiose, nigerose, and neotrehalose. This is the first report of an α-glucosidase with high activity toward neotrehalose. The transglucosylation products, nigerose, kojibiose, isomaltose, and neotrehalose, were generated from 440 mm maltose. Substitution of Tyr268, situated on the β → α loop 1 of BspAG31A, with Trp increased hydrolytic activity toward isomaltose. This mutation reduced the hydrolytic activity toward maltooligosaccharides more than toward kojibiose, nigerose, and neotrehalose. Analysis of the Y173A mutant of BspAG31A showed that Tyr173, situated on the N-terminal domain loop, is associated with the formation of subsite +2. In Y173A, the kcat/Km for maltooligosaccharides slightly decreased with an increasing degree of polymerization compared with wild type. Among the amino acid residues surrounding the substrate binding site, Val543 and Glu545 of BspAG31A were different from the corresponding residues of Bacillus thermoamyloliquefaciens α-glucosidase II, which has higher activity toward isomaltose than BspAG31A. The E545G mutation slightly enhanced isomaltase activity without a large reduction of hydrolytic activities toward other substrates. V543A showed 1.8-3.5-fold higher hydrolytic activities toward all substrates other than neotrehalose compared with wild type, although its preference for isomaltose was unchanged.
  • Naoya Tamamura, Wataru Saburi, Atsushi Mukai, Naoki Morimoto, Toshihiko Takehana, Seiji Koike, Hirokazu Matsui, Haruhide Mori
    BIOCHEMICAL ENGINEERING JOURNAL 86 8 - 15 2014年05月 [査読有り][通常論文]
     
    The hydrolytic activity of a thermophilic alkalophilic alpha-amylase from Bacillus sp. AAH-31 (AmyL) toward soluble starch was enhanced through optimization of amino acid (aa) residues situated near the substrate binding site. Twenty-four selected aa residues were replaced with Ala, and Gly429 and Gly550 were altered to Lys and Glu, respectively, based on comparison of AmyL's aa sequence with related enzymes. Y426A, H431A,I509A, and K549A showed notably higher activity than the wild type at 162-254% of wildtype activity. Tyr426, His431, and Ile509 were predicted to be located near subsite -2, while Lys549 was near subsite +2. Ser, Ala, Ala, and Met were found to be the best aa residues for the positions of Tyr426, His431, Ile509, and Lys549, respectively. Combinations of the optimized single mutations at distant positions were effective in enhancing catalytic activity. The double-mutant enzymes Y426S/K549M, H431A/K549M, and I509A/K549M, combining two of the selected single mutations, showed 340%, 252%, and 271% of wild type activity, respectively. Triple and quadruple-mutant enzymes of the selected mutations did not show higher activity than the best double-mutant, Y426S/K549M. (C) 2014 Elsevier B.V. All rights reserved.
  • Shen X, Saburi W, Gai ZQ, Komoda K, Yu J, Ojima-Kato T, Kido Y, Matsui H, Mori H, Yao M
    Acta crystallographica. Section F, Structural biology communications 70 Pt 4 464 - 466 2014年04月 [査読有り][通常論文]
     
    The alpha-glucosidase HaG from the halophilic bacterium Halomonas sp. strain H11 catalyzes the hydrolysis of the glucosidic linkage at the nonreducing end of alpha-glucosides, such as maltose and sucrose, to release alpha-glucose. Based on its amino-acid sequence, this enzyme is classified as a member of glycoside hydrolase family 13. HaG has three unique characteristics: (i) a very narrow substrate specificity, almost exclusively hydrolyzing disaccharides; (ii) activation by monovalent cations, such as K+, Rb+, Cs+ and NH4+; and (iii) high transfer activity of the glucose moiety to the OH group of low-molecular-weight compounds, including glycerol and 6-gingerol. Crystallographic studies have been performed in order to understand these special features. An expression vector was constructed and recombinant HaG protein was overexpressed, purified and crystallized. A data set to 2.15 angstrom resolution was collected and processed. The crystal belonged to space group P2(1)2(1)2(1), with unit-cell parameters a = 60.2, b = 119.2, c = 177.2 angstrom. The structure has been determined by molecular replacement using the isomaltulose synthase PalI as the search model (PDB entry 1m53).
  • Fujiwara T, Saburi W, Matsui H, Mori H, Yao M
    The Journal of biological chemistry 289 6 3405 - 3415 2014年02月 [査読有り][通常論文]
     
    Background: The details of the catalytic mechanism of cellobiose 2-epimerase (CE) remains unclear. Results: The crystal structures of Rhodothermus marinus CE in the apo form and complexes with its substrates/products 4-O--d-glucopyranosyl-d-mannnose, epilactose, or cellobiitol (reaction intermediate analog) were elucidated. Conclusion: Epimerization catalyzed by CE proceeds through ring opening, deprotonation/reprotonation, carbon-carbon bond rotation, and ring closure. Significance: This study yielded structural insights into epimerization catalyzed by CE. Cellobiose 2-epimerase (CE) reversibly converts d-glucose residues into d-mannose residues at the reducing end of unmodified 1,4-linked oligosaccharides, including -1,4-mannobiose, cellobiose, and lactose. CE is responsible for conversion of 1,4-mannobiose to 4-O--d-mannosyl-d-glucose in mannan metabolism. However, the detailed catalytic mechanism of CE is unclear due to the lack of structural data in complex with ligands. We determined the crystal structures of halothermophile Rhodothermus marinus CE (RmCE) in complex with substrates/products or intermediate analogs, and its apo form. The structures in complex with the substrates/products indicated that the residues in the 5-6 loop as well as those in the inner six helices form the catalytic site. Trp-322 and Trp-385 interact with reducing and non-reducing end parts of these ligands, respectively, by stacking interactions. The architecture of the catalytic site also provided insights into the mechanism of reversible epimerization. His-259 abstracts the H2 proton of the d-mannose residue at the reducing end, and consistently forms the cis-enediol intermediate by facilitated depolarization of the 2-OH group mediated by hydrogen bonding interaction with His-200. His-390 subsequently donates the proton to the C2 atom of the intermediate to form a d-glucose residue. The reverse reaction is mediated by these three histidines with the inverse roles of acid/base catalysts. The conformation of cellobiitol demonstrated that the deprotonation/reprotonation step is coupled with rotation of the C2-C3 bond of the open form of the ligand. Moreover, it is postulated that His-390 is closely related to ring opening/closure by transferring a proton between the O5 and O1 atoms of the ligand.
  • Jaito N, Saburi W, Odaka R, Kido Y, Hamura K, Nishimoto M, Kitaoka M, Matsui H, Mori H
    Bioscience, biotechnology, and biochemistry 78 2 263 - 270 2014年02月 [査読有り][通常論文]
     
    4-O-beta-D-Mannosyl-D-glucose phosphorylase (MGP), found in anaerobes, converts 4-O-beta-D-mannosylD- glucose (Man-Glc) to alpha-D-mannosyl phosphate and D-glucose. It participates in mannan metabolism with cellobiose 2-epimerase (CE), which converts beta-1,4-mannobiose to Man-Glc. A putative MGP gene is present in the genome of the thermophilic aerobe Rhodothermus marinus (Rm) upstream of the gene encoding CE. Konjac glucomannan enhanced production by R. marinus of MGP, CE, and extracellular mannan endo-1,4-beta-mannosidase. Recombinant RmMGP catalyzed the phosphorolysis of Man-Glc through a sequential bi-bi mechanism involving ternary complex formation. Its molecular masses were 45 and 222 kDa under denaturing and nondenaturing conditions, respectively. Its pH and temperature optima were 6.5 and 75 degrees C, and it was stable between pH 5.5-8.3 and below 80 degrees C. In the reverse reaction, RmMGP had higher acceptor preferences for 6-deoxy-D-glucose and D-xylose than R. albus NE1 MGP. In contrast to R. albus NE1 MGP, RmMGP utilized methyl beta-D-glucoside and 1,5-anhydro- D-glucitol as acceptor substrates.
  • Wataru Saburi, Momoko Kobayashi, Haruhide Mori, Masayuki Okuyama, Atsuo Kimura
    JOURNAL OF BIOLOGICAL CHEMISTRY 288 44 31670 - 31677 2013年11月 [査読有り][通常論文]
     
    Dextran glucosidase from Streptococcus mutans (SmDG) catalyzes the hydrolysis of an alpha-1,6-glucosidic linkage at the non-reducing end of isomaltooligosaccharides and dextran. This enzyme has an Asp-194 catalytic nucleophile and two catalytically unrelated Cys residues, Cys-129 and Cys-532. Cys-free SmDG was constructed by replacement with Ser (C129S/C532S (2CS), the activity of which was the same as that of the wild type, SmDG). The nucleophile mutant of 2CS was generated by substitution of Asp-194 with Cys (D194C-2CS). The hydrolytic activity of D194C-2CS was 8.1 x 10(-4) % of 2CS. KI-associated oxidation of D194C-2CS increased the activity up to 0.27% of 2CS, which was 330 times higher than D194C-2CS. Peptide-mapping mass analysis of the oxidized D194C-2CS (Ox-D194C-2CS) revealed that Cys-194 was converted into cysteine sulfinate. Ox-D194C-2CS and 2CS shared the same properties (optimum pH, pI, and substrate specificity), whereas Ox-D194C-2CS had much higher transglucosylation activity than 2CS. This is the first study indicating that a more acidic nucleophile (-SOO-) enhances transglycosylation. The introduction of cysteine sulfinate as a catalytic nucleophile could be a novel approach to enhance transglycosylation.
  • Sawano T, Saburi W, Hamura K, Matsui H, Mori H
    The FEBS journal 280 18 4463 - 4473 2013年09月 [査読有り][通常論文]
     
    Ruminococcus albus has the ability to intracellularly degrade cello-oligosaccharides primarily via phosphorolysis. In this study, the enzymatic characteristics of R. albus cellodextrin phosphorylase (RaCDP), which is a member of glycoside hydrolase family 94, was investigated. RaCDP catalyzes the phosphorolysis of cellotriose through an ordered 'bi bi' mechanism in which cellotriose binds to RaCDP before inorganic phosphate, and then cellobiose and glucose 1-phosphate (Glc1P) are released in that order. Among the cello-oligosaccharides tested, RaCDP had the highest phosphorolytic and synthetic activities towards cellohexaose and cellopentaose, respectively. RaCDP successively transferred glucosyl residues from Glc1P to the growing cello-oligosaccharide chain, and insoluble cello-oligosaccharides comprising a mean of eight residues were produced. Sophorose, laminaribiose, β-1,4-xylobiose, β-1,4-mannobiose and cellobiitol served as acceptors for RaCDP. RaCDP had very low affinity for phosphate groups in both the phosphorolysis and synthesis directions. A sequence comparison revealed that RaCDP has Gln at position 646 where His is normally conserved in the phosphate binding sites of related enzymes. A Q646H mutant showed approximately twofold lower apparent Km values for inorganic phosphate and Glc1P than the wild-type. RaCDP has Phe at position 633 corresponding to Tyr and Val in the +1 subsites of cellobiose phosphorylase and N,N′-diacetylchitobiose phosphorylase, respectively. A F633Y mutant showed higher preference for cellobiose over β-1,4-mannobiose as an acceptor substrate in the synthetic reaction than the wild-type. Furthermore, the F633Y mutant showed 75- and 1100-fold lower apparent Km values for inorganic phosphate and Glc1P, respectively, in phosphorolysis and synthesis of cellotriose. R. albus cellodextrin phosphorylase (RaCDP), classified into glycoside hydrolase family 94, was characterized. Among the cello-oligosaccharides tested, RaCDP had the highest phosphorolytic and synthetic activities towards cellohexaose and cellopentaose, respectively. Sophorose, laminaribiose, β-1,4-xylobiose, β-1,4-mannobiose, and cellobiitol served as acceptors. Site-directed mutational study revealed that Tyr633 is responsible for low affinity to the phosphate group and synthetic activity towards β-1,4-mannobiose. © 2013 FEBS.
  • Shinji Wakuta, Yumi Shibata, Yumiko Yoshizaki, Wataru Saburi, Shigeki Hamada, Hiroyuki Ito, Seon-Kap Hwang, Thomas W. Okita, Hirokazu Matsui
    BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY 77 9 1854 - 1859 2013年09月 [査読有り][通常論文]
     
    The higher plant ADP-glucose (ADPG) pyrophosphorylase (AGPase), composed of two small subunits and two large subunits (LSs), produces ADPG, the sole substrate for starch biosynthesis from alpha-D-glucose 1-phosphate and ATP. This enzyme controls a key step in starch synthesis as its catalytic activity is activated by 3-phosphoglycerate (3-PGA) and inhibited by orthophosphate (Pi). Previously, two mutations in the LS of potato AGPase (PLS), PLS-E38K and PLS-G101N, were found to increase sensitivity to 3-PGA activation and tolerance to Pi inhibition. In the present study, the double mutated enzyme (PLS-E38K/G101N) was evaluated. In a complementation assay of ADPG synthesis in an Escherichia coli mutant defective in the synthesis of ADPG, expression of PLS-E38K/G101N mediated higher glycogen production than wild-type potato AGPase (PLS-WT) and the single mutant enzymes, PLS-E38K and PLS-G101N, individually. Purified PLS-E38K/G101N showed higher sensitivity to 3-PGA activation and tolerance to Pi inhibition than PLS-E38K or PLS-G101N. Moreover, the enzyme activities of PLS-E38K, PLS-G101N, and PLS-E38K/G101N were more readily stimulated by other major phosphate-ester metabolites, such as fructose 6-phosphate, fructose 2,6-bisphosphate, and ribose 5-phosphate, than was that of PLS-WT. Hence, although the specific enzyme activities of the LS mutants toward 3-PGA were impaired to some extent by the mutations, our results suggest that their enhanced allosteric regulatory properties and the broadened effector selectivity gained by the same mutations not only offset the lowered enzyme catalytic turnover rates but also increase the net performance of potato AGPase in vivo in view of increased glycogen production in bacterial cells.
  • Saburi W, Morimoto N, Mukai A, Kim DH, Takehana T, Koike S, Matsui H, Mori H
    Bioscience, biotechnology, and biochemistry 77 9 1867 - 1873 2013年09月 [査読有り][通常論文]
     
    alpha-Amylases (EC 3.2.1.1) hydrolyze internal alpha-1,4-glucosidic linkages of starch and related glucans. Bacillus sp. AAH-31 produces an alkalophilic thermophilic alpha-amylase (AmyL) of higher molecular mass, 91 kDa, than typical bacterial alpha-amylases. In this study, the AmyL gene was cloned to determine its primary structure, and the recombinant enzyme, produced in Escherichia coli, was characterized. AmyL shows no hydrolytic activity towards pullulan,. but the central region of AmyL (Gly395-Asp684) was similar to neopullulanase-like alpha-amylases. In contrast to known neopullulanase-like alpha-amylases, the N-terminal region (Gln29-Phe102) of AmyL was similar to carbohydrate-binding module family 20 (CBM20), which is involved in the binding of enzymes to starch granules. Recombinant AmyL showed more than 95% of its maximum activity in a pH range of 8.2-10.5, and was stable below 65 degrees C and from pH 6.4 to 11.9. The k(cat) values for soluble starch, gamma-cyclodextrin, and maltotriose were 103 s(-1), 67.6 s(-1), and 5.33 s(-1), respectively, and the K-m values were 0.100 mg/mL, 0.348 mM, and 2.06 mM, respectively. Recombinant AmyL did not bind to starch granules. But the substitution of Trp45 and Trp84, conserved in site 1 of CBM20, with Ala reduced affinity to soluble starch, while the mutations did not affect affinity for oligosaccharides. Substitution of Trp61, conserved in site 2 of CBM20, with Ala enhanced hydrolytic activity towards soluble starch, indicating that site 2 of AmyL does not contribute to binding to soluble long-chain substrates.
  • Himeno N, Saburi W, Wakuta S, Takeda R, Matsuura H, Nabeta K, Sansenya S, Ketudat Cairns JR, Mori H, Imai R, Matsui H
    Bioscience, biotechnology, and biochemistry 77 5 934 - 939 2013年05月 [査読有り][通常論文]
     
    beta-Glucosidases (EC 3.2.1.21) split beta-glucosidic linkages at the non-reducing end of glucosides and oligosaccharides to release beta-D-glucose. One of the important functions of plant beta-glucosidase is deglucosylation of inactive glucosides of phytohormones to regulate levels of active hormones. Tuberonic acid is a jasmonate-related compound that shows tuber-inducing activity in the potato. We have identified two enzymes, OsTAGG1 and OsTAGG2, that have hydrolytic activity towards tuberonic acid beta-D-glucoside in rice (Oryza sativa L.). The expression of OsTAGG2 is upregulated by wounding and by methyl jasmonate, suggesting that this isozyme is involved in responses to biotic stresses and wounding, but the physiological substrate of OsTAGG2 remains ambiguous. In this study, we produced recombinant OsTAGG2 in Pichia pastoris (rOsTAGG2P), and investigated its substrate specificity in detail. From 1 L of culture medium, 2.1 mg of purified recombinant enzyme was obtained by ammonium sulfate precipitation and Ni-chelating column chromatography. The specific activity of rOsTAGG2P (182 U/mg) was close to that of the native enzyme (171 U/mg), unlike recombinant OsTAGG2 produced in Escherichia coli, which had approximately 3-fold lower specific activity than the native enzyme. The optimum pH and temperature for rOsTAGG2P were pH 3.4 and 60 degrees C. After pH and heat treatments, the enzyme retained its original activity in a pH range of 3.4-9.8 and below 55 degrees C. Native OsTAGG2 and rOsTAGG2P showed 4.5-4.7-fold higher activities towards salicylic acid beta-D-glucoside, an inactive storage-form of salicylic acid, than towards tuberonic acid beta-D-glucoside (TAG), although OsTAGG2 was originally isolated from rice based on TAG-hydrolytic activity.
  • Takaaki Fujiwara, Wataru Saburi, Sota Inoue, Haruhide Mori, Hirokazu Matsui, Isao Tanaka, Min Yao
    FEBS LETTERS 587 7 840 - 846 2013年04月 [査読有り][通常論文]
     
    Enzymatic epimerization is an important modification for carbohydrates to acquire diverse functions attributable to their stereoisomers. Cellobiose 2-epimerase (CE) catalyzes interconversion between D-glucose and D-mannose residues at the reducing end of beta-1,4-linked oligosaccharides. Here, we solved the structure of Ruminococcus albus CE (RaCE). The structure of RaCE showed strong similarity to those of N-acetyl-D-glucosamine 2-epimerase and aldose-ketose isomerase YihS with a high degree of conservation of residues around the catalytic center, although sequence identity between them is low. Based on structural comparison, we found that His184 is required for RaCE activity as the third histidine added to two essential histidines in other sugar epimerases/isomerases. This finding was confirmed by mutagenesis, suggesting a new catalytic mechanism for CE involving three histidines. Structured summary of protein interactions: RaCE and X-ray crystallography (View interaction) (C) 2013 Federation of European Biochemical Societies. Published by Elsevier B. V. All rights reserved.
  • Teruyo Ojima, Wataru Saburi, Takeshi Yamamoto, Haruhide Mori, Hirokazu Matsui
    BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY 77 1 189 - 193 2013年01月 [査読有り][通常論文]
     
    Cellobiose 2-epimerase (CE), found mainly in anaerobes, reversibly converts D-glucose residues at the reducing end of beta-1,4-linked oligosaccharides to D-mannose residues. In this study, we characterized CE-like proteins from various aerobes (Flavobacterium johnsoniae NBRC 14942, Pedobacter heparinus NBRC 12017, Dyadobacter fermentans ATCC 700827, Herpetosiphon aurantiacus ATCC 23779, Saccharophagus degradans ATCC 43961, Spirosoma linguale ATCC 33905, and Teredinibacter turnerae ATCC 39867), because aerobes, more easily cultured on a large scale than anaerobes, are applicable in industrial processes. The recombinant CE-like proteins produced in Escherichia coli catalyzed epimerization at the C2 position of cellobiose, lactose, epilactose, and beta-1,4-mannobiose, whereas N-acetyl-D-glucosamine, N-acetyl-D-mannosamine, D-glucose, and D-mannose were inert as substrates. All the CEs, except for P. heparinus CE, the optimum pH of which was 6.3, showed highest activity at weakly alkaline pH. CEs from D. fermentans, H. aurantiacus, and S. linguale showed higher optimum temperatures and thermostability than the other enzymes analyzed. The enzymes from D. fermentans, S. linguale, and T. turnerae showed significantly high k(cat) and K-m values towards cellobiose and lactose. Especially, T. turnerae CE showed a very high k(cat) value towards lactose, an attractive property for the industrial production of epilactose, which is carried out at high substrate concentrations.
  • Ken Hamura, Wataru Saburi, Hirokazu Matsui, Haruhide Mori
    Carbohydrate Research 379 21 - 25 2013年 [査読有り][通常論文]
     
    Cellobiose phosphorylase (EC 2.4.1.20, CBP) catalyzes the reversible phosphorolysis of cellobiose to α-D-glucose 1-phosphate (Glc1P) and D-glucose. Cys485, Tyr648, and Glu653 of CBP from Ruminococcus albus, situated at the +1 subsite, were mutated to modulate acceptor specificity. C485A, Y648F, and Y648V were active enough for analysis. Their acceptor specificities were compared with the wild type based on the apparent kinetic parameters determined in the presence of 10 mM Glc1P. C485A showed higher preference for D-glucosamine than the wild type. Apparent kcat/Km values of Y648F for D-mannose and 2-deoxy-D-glucose were 8.2- and 4.0-fold higher than those of the wild type, respectively. Y648V had synthetic activity toward N-acetyl-D-glucosamine, while the other variants did not. The oligosaccharide production in the presence of the same concentrations of wild type and each mutant was compared. C485A produced 4-O-β-D-glucopyranosyl-D-glucosamine from 10 mM Glc1P and D-glucosamine at a rate similar to the wild type. Y648F and Y648V produced 4-O-β-D-glucopyranosyl-D-mannose and 4-O-β-D- glucopyranosyl-N-acetyl-D-glucosamine much more rapidly than the wild type when D-mannose and N-acetyl-D-glucosamine were used as acceptors, respectively. After a 4 h reaction, the amounts of 4-O-β-D-glucopyranosyl-D-mannose and 4-O-β-D-glucopyranosyl-N-acetyl-D-glucosamine produced by Y648F and Y648V were 5.9- and 12-fold higher than the wild type, respectively. © 2013 Elsevier Ltd.
  • Myung-Hee Kim, Shunya Sato, Kentaro Sasaki, Wataru Saburi, Hirokazu Matsui, Ryozo Imai
    FEBS OPEN BIO 3 438 - 442 2013年 [査読有り][通常論文]
     
    Cold shock proteins (CSPs) of bacteria are produced in response to cold and function as RNA chaperones that are essential for cold adaptation. Arabidopsis thaliana COLD SHOCK DOMAIN PROTEIN 3 (AtCSP3) shares a domain with bacterial CSPs and is involved in acquisition of freezing tolerance. Our previous study revealed that many of the genes that are down regulated in an AtCSP3 knockout mutant (atcsp3-2) are functionally associated with responses to salt and drought as well as cold. Here, we examined the involvement of AtCSP3 in salt and drought stress tolerance. We found that AtCSP3 is induced during salt and drought stresses, and is regulated by ABA. Pi knockout mutant of AtCSP3 (atcsp3-2) showed lower survival rates after salt and drought stress treatments. Conversely, the AtCSP3-overexpressing plants displayed higher survival rates after treatment with these stresses. Most of the genes that were down regulated in the atcsp3-2 mutant were found to be inducible upon salt and drought stresses, and upregulated in the AtCSP3-overexpressors. Together, our data demonstrates that AtCSP3 is involved in the regulation of salt and drought stress tolerance in Arabidopsis. (C) 2013 The Authors. Published by Elsevier B.V. oil behalf of Federation of European Biochemical Societies. All rights reserved.
  • Kawahara R, Saburi W, Odaka R, Taguchi H, Ito S, Mori H, Matsui H
    The Journal of biological chemistry 287 50 42389 - 42399 50 2012年12月 [査読有り][通常論文]
     
    Ruminococcus albus is a typical ruminal bacterium digesting cellulose and hemicellulose. Cellobiose 2-epimerase (CE; EC 5.1.3.11), which converts cellobiose to 4-O-beta-D-glucosyl-D-mannose, is a particularly unique enzyme in R. albus, but its physiological function is unclear. Recently, a new metabolic pathway of mannan involving CE was postulated for another CE-producing bacterium, Bacteroides fragilis. In this pathway, beta-1,4-mannobiose is epimerized to 4-O-beta-D-mannosyl-D-glucose (Man-Glc) by CE, and Man-Glc is phosphorolyzed to alpha-D-mannosyl 1-phosphate (Man1P) and D-glucose by Man-Glc phosphorylase (MP; EC 2.4.1.281). Ruminococcus albus NE1 showed intracellular MP activity, and two MP isozymes, RaMP1 and RaMP2, were obtained from the cell-free extract. These enzymes were highly specific for the mannosyl residue at the non-reducing end of the substrate and catalyzed the phosphorolysis and synthesis of Man-Glc through a sequential Bi Bi mechanism. In a synthetic reaction, RaMP1 showed high activity only toward D-glucose and 6-deoxy-D-glucose in the presence of Man1P, whereas RaMP2 showed acceptor specificity significantly different from RaMP1. RaMP2 acted on D-glucose derivatives at the C2- and C3-positions, including deoxy- and deoxyfluoro-analogues and epimers, but not on those substituted at the C6-position. Furthermore, RaMP2 had high synthetic activity toward the following oligosaccharides: beta-linked glucobioses, maltose, N, N'-diacetylchitobiose, and beta-1,4-mannooligosaccharides. Particularly, beta-1,4-mannooligosaccharides served as significantly better acceptor substrates for RaMP2 than D-glucose. In the phosphorolytic reactions, RaMP2 had weak activity toward beta-1,4-mannobiose but efficiently degraded beta-1,4-mannooligosaccharides longer than beta-1,4-mannobiose. Consequently, RaMP2 is thought to catalyze the phosphorolysis of beta-1,4-mannooligosaccharides longer than beta-1,4-mannobiose to produce Man1P and beta-1,4-mannobiose.
  • Young-Min Kim, Eiji Yamamoto, Min-Sun Kang, Hiroyuki Nakai, Wataru Saburi, Masayuki Okuyama, Haruhide Mori, Kazumi Funane, Mitsuru Momma, Zui Fujimoto, Mikihiko Kobayashi, Doman Kim, Atsuo Kimura
    FEBS JOURNAL 279 17 3185 - 3191 2012年09月 [査読有り][通常論文]
     
    Bacteroides thetaiotaomicron VPI-5482 harbors a gene encoding a putative cycloisomaltooligosaccharide glucanotransferase (BT3087) belonging to glycoside hydrolase family 66. The goal of the present study was to characterize the catalytic properties of this enzyme. Therefore, we expressed BT3087 (recombinant endo-dextranase from Bacteroides thetaiotaomicron VPI-5482) in Escherichia coli and determined that recombinant endo-dextranase from Bacteroides thetaiotaomicron VPI-5482 preferentially synthesized isomaltotetraose and isomaltooligosaccharides (degree of polymerization > 4) from dextran. The enzyme also generated large cyclic isomaltooligosaccharides early in the reaction. We conclude that members of the glycoside hydrolase 66 family may be classified into three types: (a) endo-dextranases, (b) dextranases possessing weak cycloisomaltooligosaccharide glucanotransferase activity, and (c) cycloisomaltooligosaccharide glucanotransferases.
  • Hiroki Sato, Wataru Saburi, Teruyo Ojima, Hidenori Taguchi, Haruhide Mori, Hirokazu Matsui
    BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY 76 8 1584 - 1587 2012年08月 [査読有り][通常論文]
     
    Cellobiose 2-epimerase (CE) efficiently forms epilactose which has several beneficial biological functions. A thermostable CE from Rhodothermus marinus was immobilized on Duolite A568 and packed into a column. Lactose (100 g/L) was supplied to the reactor, kept at 50 degrees C at a space velocity of 8h(-1). The epilactose concentration of the resulting eluate was 30 g/L, and this was maintained for 13d.
  • Kim DH, Morimoto N, Saburi W, Mukai A, Imoto K, Takehana T, Koike S, Mori H, Matsui H
    Bioscience, biotechnology, and biochemistry 76 7 1378 - 1383 7 2012年07月 [査読有り][通常論文]
     
    α-Amylase (EC 3.2.1.1) hydrolyzes an internal α-1,4-glucosidic linkage of starch and related glucans. Alkalophilic liquefying enzymes from Bacillus species are utilized as additives in dishwashing and laundry detergents. In this study, we found that Bacillus sp. AAH-31, isolated from soil, produced an alkalophilic liquefying α-amylase with high thermostability. Extracellular α-amylase from Bacillus sp. AAH-31 (AmyL) was purified in seven steps. The purified enzyme showed a single band of 91 kDa on SDS–PAGE. Its specific activity of hydrolysis of 0.5% soluble starch was 16.7 U/mg. Its optimu...
  • Young-Min Kim, Yoshiaki Kiso, Tomoe Muraki, Min-Sun Kang, Hiroyuki Nakai, Wataru Saburi, Weeranuch Lang, Hee-Kwon Kang, Masayuki Okuyama, Haruhide Mori, Ryuichiro Suzuki, Kazumi Funane, Nobuhiro Suzuki, Mitsuru Momma, Zui Fujimoto, Tetsuya Oguma, Mikihiko Kobayashi, Doman Kim, Atsuo Kimura
    JOURNAL OF BIOLOGICAL CHEMISTRY 287 24 19927 - 19935 2012年06月 [査読有り][通常論文]
     
    A novel endodextranase from Paenibacillus sp. (Paenibacillus sp. dextranase; PsDex) was found to mainly produce isomaltotetraose and small amounts of cycloisomaltooligosaccharides (CIs) with a degree of polymerization of 7-14 from dextran. The 1,696-amino acid sequence belonging to the glycosyl hydrolase family 66 (GH-66) has a long insertion (632 residues; Thr(451)-Val(1082)), a portion of which shares identity (35% at Ala(39)-Ser(1304) of PsDex) with Pro(32)-Ala(755) of CI glucanotransferase (CITase), a GH-66 enzyme that catalyzes the formation of CIs from dextran. This homologous sequence (Val(837)-Met(932) for PsDex and Tyr(404)-Tyr(492) for CITase), similar to carbohydrate-binding module 35, was not found in other endodextranases (Dexs) devoid of CITase activity. These results support the classification of GH-66 enzymes into three types: (i) Dex showing only dextranolytic activity, (ii) Dex catalyzing hydrolysis with low cyclization activity, and (iii) CITase showing CI-forming activity with low dextranolytic activity. The fact that a C-terminal truncated enzyme (having Ala(39)-Ser(1304)) has 50% wild-type PsDex activity indicates that the C-terminal 392 residues are not involved in hydrolysis. GH-66 enzymes possess four conserved acidic residues (Asp(189), Asp(340), Glu(412), and Asp(1254) of PsDex) of catalytic candidates. Their amide mutants decreased activity (1/1,500 to 1/40,000 times), and D1254N had 36% activity. A chemical rescue approach was applied to D189A, D340G, and E412Q using alpha-isomaltotetraosyl fluoride with NaN3. D340G or E412Q formed a beta- or alpha-isomaltotetraosyl azide, respectively, strongly indicating Asp(340) and Glu(412) as a nucleophile and acid/base catalyst, respectively. Interestingly, D189A synthesized small sized dextran from alpha-isomaltotetraosyl fluoride in the presence of NaN3.
  • Ojima T, Aizawa K, Saburi W, Yamamoto T
    Carbohydrate research 354 59 - 64 2012年06月 [査読有り][通常論文]
     
    6-Gingerol [(S)-5-hydroxy-1-(4-hydroxy-3-methoxyphenyl)decan-3-one] is a biologically active compound and is abundant in the rhizomes of ginger (Zingiber officinale). It has some beneficial functions in healthcare, but its use is limited because of its insolubility in water and its heat-instability. To improve these physical properties, the glucosylation of 6-gingerol was investigated using alpha-glucosidases (EC. 3.2.1.20) from Aspergillus niger, Aspergillus nidulans ABPU1, Acremonium strictum, Halomonas sp. H11, and Saccharomyces cerevisiae, and cyclodextrin glucanotransferases (CGTase, EC. 2.4.1.19) from Bacillus coagulans, Bacillus sp. No. 38-2, Bacillus clarkii 7364, and Geobacillus stearothermophilus. Among these, only alpha-glucosidase from Halomonas sp. H11 (HaG) transferred a glucosyl moiety to 6-gingerol, and produced glucosylated compounds. The chemical structure of the reaction product, determined by nuclear magnetic resonance spectroscopy and mass spectrometry, was (S)-5-(O-alpha-D-glucopyranosyl)-1-(4-hydroxy-3-methoxyphenyl) decan-3-one (5-alpha-Glc-gingerol). Notably, the regioisomer formed by glucosylation of the phenolic OH was not observed at all, indicating that HaG specifically transferred the glucose moiety to the 5-OH of the beta-hydroxy keto group in 6-gingerol. Almost 60% of the original 6-gingerol was converted into 5-alpha-Glc-gingerol by the reaction. In contrast to 6-gingerol, 5-alpha-Glc-gingerol, in the form of an orange powder prepared by freeze-drying, was water-soluble and stable at room temperature. It was also more stable than 6-gingerol under acidic conditions and to heat. (C) 2012 Elsevier Ltd. All rights reserved.
  • Kim YM, Saburi W, Yu S, Nakai H, Maneesan J, Kang MS, Chiba S, Kim D, Okuyama M, Mori H, Kimura A
    The Journal of biological chemistry 287 27 22441 - 22444 27 2012年06月 [査読有り][通常論文]
     
    alpha-Glucosidase is in the glycoside hydrolase family 13 (13AG) and 31 (31AG). Only 31AGs can hydrate the D-glucal double bond to form alpha-2-deoxyglucose. Because 1,5-anhydrofructose (AF), having a 2-OH group, mimics the oxocarbenium ion transition state, AF may be a substrate for alpha-glucosidases. alpha-Glucosidase-catalyzed hydration produced alpha-glucose from AF, which plateaued with time. Combined reaction with alpha-1,4-glucan lyase and 13AG eliminated the plateau. Aspergillus niger alpha-glucosidase (31AG), which is stable in organic solvent, produced ethyl alpha-glucoside from AF in 80% ethanol. The findings indicate that alpha-glucosidases catalyze trans-addition. This is the first report of alpha-glucosidase-associated glucose formation from AF, possibly contributing to the salvage pathway of unutilized AF.
  • Ken Hamura, Wataru Saburi, Shotaro Abe, Naoki Morimoto, Hidenori Taguchi, Haruhide Mori, Hirokazu Matsui
    BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY 76 4 812 - 818 2012年04月 [査読有り][通常論文]
     
    Cellobiose phosphorylase (CBP) catalyzes the reversible phosphorolysis of cellobiose to produce alpha-D-glucopyranosyl phosphate (Glc1P) and D-glucose. It is an essential enzyme for the metabolism of cello-oligosaccharides in a ruminal bacterium, Ruminococcus albus. In this study, recombinant R. albus CBP (RaCBP) produced in Escherichia coli was characterized. It showed highest activity at pH 6.2 at 50 degrees C, and was stable in a pH range of 5.5-8.8 and at below 40 degrees C. It phosphorolyzed only cellobiose efficiently, and the reaction proceeded through a random-ordered bi hi mechanism, by which inorganic phosphate and cellobiose bind in random order and D-glucose is released before Glc1P. In the synthetic reaction, RaCBP showed highest activity to D-glucose, followed by 6-deoxy-D-glucose. D-Mannose, 2-deoxy-D-glucose, D-glucosamine, D-xylose, 1,5-anhydro-D-glucitol, and gentiobiose also served as acceptors, although the activities for them were much lower than for D-glucose. D-Glucose acted as a competitive-uncompetitive inhibitor of the reverse synthetic reaction, which bound not only the Glc1P site (competitive) but also the ternary enzyme-Glc1P-D-glucose complex (uncompetitive).
  • Ojima T, Saburi W, Yamamoto T, Kudo T
    Applied and environmental microbiology 78 6 1836 - 1845 6 2012年03月 [査読有り][通常論文]
     
    An alpha-glucosidase (HaG) with the following unique properties was isolated from Halomonas sp. strain H11: (i) high transglucosylation activity, (ii) activation by monovalent cations, and (iii) very narrow substrate specificity. The molecular mass of the purified HaG was estimated to be 58 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). HaG showed high hydrolytic activities toward maltose, sucrose, and p-nitrophenyl alpha-D-glucoside (pNPG) but to almost no other disaccharides or malto-oligosaccharides higher than trisaccharides. HaG showed optimum activity to maltose at 30 degrees C and pH 6.5. Monovalent cations such as K+, Rb+, Cs+, and NH4+ increased the enzymatic activity to 2- to 9-fold of the original activity. These ions shifted the activity-pH profile to the alkaline side. The optimum temperature rose to 40 degrees C in the presence of 10 mM NH4+, although temperature stability was not affected. The apparent K-m and k(cat) values for maltose and pNPG were significantly improved by monovalent cations. Surprisingly, k(cat)/K-m for pNPG increased 372- to 969-fold in their presence. HaG used some alcohols as acceptor substrates in transglucosylation and was useful for efficient synthesis of alpha-D-glucosylglycerol. The efficiency of the production level was superior to that of the previously reported enzyme Aspergillus niger alpha-glucosidase in terms of small amounts of by-products. Sequence analysis of HaG revealed that it was classified in glycoside hydrolase family 13. Its amino acid sequence showed high identities, 60%, 58%, 57%, and 56%, to Xanthomonas campestris WU-9701 alpha-glucosidase, Xanthomonas campestris pv. raphani 756C oligo-1,6-glucosidase, Pseudomonas stutzeri DSM 4166 oligo-1,6-glucosidase, and Agrobacterium tumefaciens F2 alpha-glucosidase, respectively.
  • Teruyo Ojima, Wataru Saburi, Hiroki Sato, Takeshi Yamamoto, Haruhide Mori, Hirokazu Matsui
    BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY 75 11 2162 - 2168 2011年11月 [査読有り][通常論文]
     
    Cellobiose 2-epimerase (CE) reversibly converts glucose residue to mannose residue at the reducing end of beta-1,4-linked oligosaccharides. It efficiently produces epilactose carrying prebiotic properties from lactose, but the utilization of known CEs is limited due to thermolability. We focused on thermoholophilic Rhodothermus marinus JCM9785 as a CE producer, since a CE-like gene was found in the genome of R. marinas DSM4252. CE activity was detected in the cell extract of R. marinus JCM9785. The deduced amino acid sequence of the CE gene from R. marinus JCM9785 (RmCE) was 94.2% identical to that from R. marinus DSM4252. The N-terminal amino acid sequence and tryptic peptide masses of the native enzyme matched those of RmCE. The recombinant RmCE was most active at 80 degrees C at pH 6.3, and stable in a range of pH 3.2-10.8 and below 80 degrees C. In contrast to other CEs, RmCE demonstrated higher preference for lactose over cellobiose.
  • Shinji Wakuta, Erika Suzuki, Wataru Saburi, Hideyuki Matsuura, Kensuke Nabeta, Ryozo Imai, Hirokazu Matsui
    BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS 409 4 634 - 639 2011年06月 [査読有り][通常論文]
     
    The synthesis of JA-IIe was catalysed by JA-Ile synthase, which is a member of the group I GH3 family of proteins. Here, we showed evidence that OsGH3.5 (OsJAR1) and OsGH3.3 (OsJAR2) are the functional JA-Ile synthases in rice, using recombinant proteins. The expression levels of OsJAR1 and OsJAR2 were induced in response to wounding with the concomitant accumulation of JA-Ile. In contrast, only the expression of OsJAR1 was associated with the accumulation of JA-Ile after blast infection. Our data suggest that these two JA-Ile synthases are differentially involved in the activation of JA signalling in response to wounding and pathogen challenge in rice. (C) 2011 Elsevier Inc. All rights reserved.
  • 田口 秀典, 鈴木 卓弥, 西向 めぐみ, 横嶋 悟, 小島 晃代, 山本 健, 佐分利 亘, 原 博, 金田 勇, 小野寺 秀一, 塩見 徳夫, 松井 博和
    Journal of Applied Glycoscience Supplement 2011 0 74 - 74 The Japanese Society of Applied Glycoscience 2011年 [査読有り][通常論文]
  • Takuya Suzuki, Megumi Nishimukai, Aki Shinoki, Hidenori Taguchi, Satoru Fukiya, Atsushi Yokota, Wataru Saburi, Takeshi Yamamoto, Hiroshi Hara, Hirokazu Matsui
    JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 58 19 10787 - 10792 2010年10月 [査読有り][通常論文]
     
    Gastrectomy often results in osteopenia and anemia because of calcium (Ca) and iron (Fe) malabsorption. Here, we investigated the effects of feeding epilactose, a non-digestible disaccharide, on gastrectomy-induced osteopenia, anemia, and Ca and Fe malabsorption in male Sprague Dawley rats. Totally gastrectomized or sham-operated rats were fed the control or epilactose (50 g/kg) diets for 30 days. Gastrectomy severely decreased intestinal Ca and Fe absorption, femoral bone strength, Ca content, hemoglobin concentration, and hematocrit. These decreases were partly or totally restored by feeding epilactose. Feeding epilactose increased the cecal tissue weight and the soluble Ca concentration and short-chain fatty acid pools of the cecal contents. Collectively, the increases in cecal mucosal area and/or soluble Ca concentration of the cecal contents, resulting from short-chain fatty acid production by intestinal microbes, are thought to be responsible for the epilactose-mediated promotion of Ca and Fe absorption in the gastrectomized rats.
  • 鈴木 卓弥, 西向 めぐみ, 田口 秀典, 濱田 茂樹, 佐分利 亘, 山本 健, 伊藤 進, 原 博, 松井 博和
    Journal of Applied Glycoscience Supplement 2010 90 - 90 日本応用糖質科学会 2010年
  • 中塚 大地, 本同 宏成, 大塚 博昭, 佐分利 亘, 森 春英, 奥山 正幸, 木村 淳夫
    Journal of Applied Glycoscience Supplement 2009 34 - 34 日本応用糖質科学会 2009年
  • Wataru Saburi, Hironori Hondoh, Young-Min Kim, Haruhide Mori, Masayuki Okuyama, Atsuo Kimura
    BIOLOGIA 63 6 1000 - 1005 2008年12月 [査読有り][通常論文]
     
    Dextran glucosidase from Streptococcus mutans (SMDG), an exo-type glucosidase of glycoside hydrolase (GH) family 13, specifically hydrolyzes an alpha-1,6-glucosidic linkage at the non-reducing ends of isomaltooligosaccharides and dextran. SMDG shows the highest sequence similarity to oligo-1,6-glucosidases (O16Gs) among GH family 13 enzymes, but these enzymes are obviously different in terms of substrate chain length specificity. SMDG efficiently hydrolyzes both short- and long-chain substrates, while O16G acts on only short- chain substrates. We focused on this difference in substrate specificity between SMDG and O16G, and elucidated the structure-function relationship of substrate chain length specificity in SMDG. Crystal structure analysis revealed that SMDG consists of three domains, A, B, and C, which are commonly found in other GH family 13 enzymes. The structural comparison between SMDG and O16G from Bacillus cereus indicated that Trp238, spanning subsites +1 and +2, and short beta -> alpha loop 4, are characteristic of SMDG, and these structural elements are predicted to be important for high activity toward long-chain substrates. The substrate size preference of SMDG was kinetically analyzed using two mutants: (i) Trp238 was replaced by a smaller amino acid, alanine, asparagine or proline; and (ii) short beta -> alpha loop 4 was exchanged with the corresponding loop of O16G. Mutant enzymes showed lower preference for long-chain substrates than wild-type enzyme, indicating that these structural elements are essential for the high activity toward long-chain substrates, as implied by structural analysis.
  • Nakagawa Y, Saburi W, Takada M, Hatada Y, Horikoshi K
    Biochimica et biophysica acta 1784 12 2004 - 2011 2008年12月 [査読有り][通常論文]
  • Masayuki Okuyama, Haruhide Mori, Hironori Hondoh, Hiroyuki Nakai, Wataru Saburi, Min Sung Kang, Young Min Kim, Mamoru Nishimoto, Jintanart Wongchawalit, Takeshi Yamamoto, Mee Son, Jin Ha Lee, San San Mar, Kenji Fukuda, Seiya Chiba, Atsuo Kimura
    Carbohydrate-Active Enzymes: Structure, Function and Applications 64 - 76 2008年09月 [査読有り][通常論文]
     
    α-Glucosidase (EC 3.2.1.20), an exo-glycosylase to hydrolyze α-glucosidic linkage, is characterized by the variety of substrate specificity. Enzyme also catalyzes the transglucosylation, on which industrial interests focus due to the production of valuable glucooligosaccharides. α-Glucosidase is a physiologically important enzyme in most of organisms (microorganisms, insects, plants and animals including human). Therefore, there are many types of α-glucosidases to display unique functions, in which we are interested. This report describes the recently analyzed unique functions of α-glucosidases by mainly focusing on honeybee α-glucosidase isoenzymes, dextran glucosidase, multiple forms of rice α-glucosidases, and Escherichia coli α-xylosidase. © 2008 Woodhead Publishing Limited. All rights reserved.
  • Hironori Hondoh, Wataru Saburi, Haruhide Mori, Masayuki Okuyama, Toshitaka Nakada, Yoshiki Matsuura, Atsuo Kimura
    JOURNAL OF MOLECULAR BIOLOGY 378 4 913 - 922 2008年05月 [査読有り][通常論文]
     
    We have determined the crystal structure of Streptococcus mutans dextran glucosidase, which hydrolyzes the alpha-1,6-glucosidic linkage of isomaltooli-gosaccharides from their non-reducing ends to produce alpha-glucose. By using the mutant of catalytic acid Glu236 -> Gln, its complex structure with the isomaltotriose, a natural substrate of this enzyme, has been determined. The enzyme has 536 amino acid residues and a molecular mass of 62,001 Da. The native and the complex structures were determined by the molecular replacement method and refined to 2.2 angstrom resolution, resulting in a final R-factor of 18.3% for significant reflections in the native structure and 18.4% in the complex structure. The enzyme is composed of three domains, A, B and C, and has a (beta/alpha)(8)-barrel in domain A, which is common to the alpha-amylase family enzymes. Three catalytic residues are located at the bottom of the active site pocket and the bound isomaltotriose occupies subsites -1 to +2. The environment of the glucose residue at subsite -1 is similar to the environment of this residue in the alpha-amylase family. Hydrogen bonds between Asp60 and Arg398 and O4 atom of the glucose unit at subsite -1 accomplish recognition of the non-reducing end of the bound substrate. The side-chain atoms of Glu371 and Lys275 form hydrogen bonds with the O2 and O3 atoms of the glucose residue at subsite +1. The positions of atoms that compose the scissile alpha-1,6-glucosidic linkage (C1, O6 and C6 atoms) are identical with the positions of the atoms in the scissile alpha-1,4 linkage (C1, O4 and C4 atoms) of maltopentaose in the alpha-amylase structure from Bacillus subtilis. The comparison with the alpha-amylase suggests that Val195 of the dextran glucosidase and the corresponding residues of alpha-1,6-hydrolyzing enzymes participate in the determination of the substrate specificity of these enzymes. (c) 2008 Elsevier Ltd. All rights reserved.
  • Wataru Saburi, Hironori Hondoh, Hideaki Unno, Masayuki Okuyama, Haruhide Mori, Toshitaka Nakada, Yoshiki Matsuura, Atsuo Kimura
    ACTA CRYSTALLOGRAPHICA SECTION F-STRUCTURAL BIOLOGY AND CRYSTALLIZATION COMMUNICATIONS 63 Pt 9 774 - 776 2007年09月 [査読有り][通常論文]
     
    Dextran glucosidase from Streptococcus mutans is an exo-hydrolase that acts on the nonreducing terminal alpha-1,6-glucosidic linkage of oligosaccharides and dextran with a high degree of transglucosylation. Based on amino-acid sequence similarity, this enzyme is classified into glycoside hydrolase family 13. Recombinant dextran glucosidase was purified and crystallized by the hanging-drop vapour-diffusion technique using polyethylene glycol 6000 as a precipitant. The crystals belong to the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 72.72, b = 86.47, c = 104.30 angstrom. A native data set was collected to 2.2 angstrom resolution from a single crystal.
  • Saburi W, Mori H, Saito S, Okuyama M, Kimura A
    Biochimica et biophysica acta 1764 4 688 - 698 2006年04月 [査読有り][通常論文]
     
    Dextran glucosidase from Streptococcus mutans (SMDG) and Bacillus oligo-1,6-glucosidases, members of glycoside hydrolase family 13 enzymes, have the high sequence similarity. Each of them is specific to alpha-1,6-glucosidic linkage at the non-reducing end of substrate to liberate glucose. The activities toward long isomaltooligosaccharides were different in both enzymes, in which SMDG and oligo-1,6-glucosidase showed high and low activities, respectively. We determined the structural elements essential for high activity toward long-chain substrate. From conformational comparison between SMDG and B. cereus oligo-1,6-glucosidase (three-dimensional structure has been solved), Trp238 and short beta -> alpha loop 4 of SMDG were considered to contribute to the high activity to long-chain substrate. W238A had similar k(cat)/k(m) value for isomaltotriose to that for isomaltose, suggesting that the affinity of subsite +2 was decreased by Trp238 replacement. Trp238 mutants as well as the chimeric enzyme having longer beta -> alpha loop 4 of B. subtilis oligo- 1,6-glucosidase showed lower preference for long-chain substrates, indicating that both Trp238 and short beta ->alpha loop 4 were important for high activity to long-chain substrates. (c) 2006 Elsevier B.V. All rights reserved.
  • Kim YM, Okuyama M, Mori H, Nakai H, Saburi W, Chiba S, Kimura A
    Tetrahedron Asymmetry 16 2 403 - 409 2005年01月24日 [査読有り][通常論文]
     
    Aspergillus niger α-glucosidase (ANGase) was used for an efficient syntheses of alkyl α-d-2-deoxyglucosides (A2DGs) and for regioselectivity studies of alkoxy-hydro additions of d-glucal in the presence of alkyl alcohols. ANGase showed a high stability with respect to the high concentration of alkyl alcohols. The reaction conditions were optimized for pH, temperature, alkyl alcohol concentration, and d-glucal concentration. On the basis of MS and NMR analyses, A2DGs were confirmed to have only an α-2-deoxyglucosidic bond and the two-dimensional NMR (HMBC) spectra showed to be made up of 2-deoxyglucosyl and alkyl moieties. © 2004 Elsevier Ltd. All rights reserved.
  • Nakai H, Okuyama M, Kim YM, Saburi W, Wongchawalit J, Mori H, Chiba S, Kimura A
    Biologia, Bratislava 60 131 - 135 2005年 [査読有り][通常論文]
  • Takuma Sano, Mamoru Nishimoto, Wataru Saburi, Atsuo Kimura, Hiroshi Yasuda, Masahiro Uchibatake, Takuji Ohwada, Hiroshi Masuda
    Plant Science 167 6 1211 - 1217 2004年12月 [査読有り][通常論文]
     
    We found P-19.5 protein that preferentially accumulated in cell clusters and globular embryos at the early stage of carrot somatic embryogenesis. P-19.5 protein was isolated from 9-day-old cell clusters with SDS-PAGE, and then determined the amino acid sequences of a N-terminal peptide and some internal peptides. Using each primer for these peptides, the full-length sequence of cDNA encoding P-19.5 protein was determined by analyzing 3′-RACE and 5′-RACE products. We regard P-19.5 protein as an allergen-like protein because the P-19.5 protein sequence predicted from cDNA was homologous to celery major allergen (75%), carrot major allergen (70-72%), Pimpinella brachycarpa pathogenesis-related protein (71%), and parsley pathogenesis-related protein (63%). We found concomitantly two separate cDNAs (P-16 and P-19.5 H cDNAs) during analyzing P-19.5 cDNA: P-16 cDNA was cloned and isolated from P-16 protein that was recognized against P-19.5 protein antiserum, and P-19.5 H cDNA that had homology (80.5% amino acid identity) with P-19.5 cDNA was detected during analyzing P-19.5 cDNA. Northern blotting revealed that P-19.5 and P-19.5 H transcripts were highly expressed at early stages of cell cluster and globular embryos, whereas P-16 transcript was invariably expressed at all stages from cell clusters to plantlets. © 2004 Elsevier Ireland Ltd. All rights reserved.

MISC

所属学協会

  • 日本応用糖質科学会   日本農芸化学会   

共同研究・競争的資金等の研究課題

  • 日本学術振興会:科学研究費助成事業
    研究期間 : 2021年07月 -2024年03月 
    代表者 : 今井 亮三, 佐分利 亘
  • 日本学術振興会:科学研究費助成事業 基盤研究(C)
    研究期間 : 2021年04月 -2024年03月 
    代表者 : 佐分利 亘
     
    糖質の高度利用には,希少糖質の効率合成法が必要である.本研究では,微生物の多様な糖質代謝を支える異性化酵素の中でも,セロビオース2-エピメラーゼやマンノースイソメラーゼなど様々な糖質異性化酵素を含む酵素群に注目し,反応特異性を制御する機構の解明と高活性変異酵素の開発を目的とした.セロビオース2-エピメラーぜの中にはエピメラーゼ活性のみを示す酵素 (1機能CE) とエピメラーゼ活性に加えてイソメラーゼ活性を示す酵素 (2機能CE) が存在するが,この特異性の違いを説明する構造は明らかではなかった.そこで,1機能CEと2機能CEの間で構造領域を入れ換えた一連のキメラ酵素を作成した.具体的には,(α/α)6バレルの触媒ドメインを構成するαヘリックス1と2,3と4,5と6,7と8,9と10,11と12について,1機能酵素の構造を2機能酵素に移植した.これら6つのキメラ酵素のうち,最初の3つの変異酵素は活性型酵素として得られた.この機能について解析を進めている. マンノースエピメラーゼ (ME酵素) については高活性変異酵素の取得のため,ハイスループットスクリーニング系を検討した.本スクリーニング系では,マンノーストランスポーター遺伝子を欠失させることでマンノース資化性を失われた大腸菌を用い,この細胞表層にME酵素を発現させることでマンノース資化性の回復,また,活性に応じた生育速度の増加により高活性変異酵素をスクリーニングすることを計画した.マンノーストランスポーターを構成する3タンパク質全ての遺伝子を欠失させることでマンノース資化性を完全に失わせることができた.この大腸菌変異株をホストとし,氷核タンパク質のNドメインを付加したME酵素を発現させると,ME酵素は外膜画分に生産され,マンノース資化性の回復が確認された.この系を利用して高活性変異酵素をスクリーニングする予定である.
  • 日本学術振興会:科学研究費助成事業 基盤研究(B)
    研究期間 : 2019年04月 -2022年03月 
    代表者 : 戸田 雅子, 佐分利 亘, 比能 洋, 新谷 尚弘
     
    真菌類や植物には結合様式の異なる様々なα型とβ型のマンナン(D-マンノ-スを含む多糖類)が含まれる。マンナンは「免疫系に対する機能を持つ食品成分」と注目され、その機能性の科学的解析が求められている。本研究はマンノ-ス骨格を持つ分子の免疫学的な意義を明らかすることを目的とする。また、日本の国菌と言われる「麹菌」を用いてマンノシル化アレルゲンを発現する麹菌を構築し、抗アレルギ-作用を持つマンナン分子の作製を目指す。本年度はまずβ型マンノオリゴ糖の調製を行い、その免疫機能性を解析した。その結果、β-Man-(1→4)-Manやβ-Man-(1→4)-Glc骨格を持つオリゴ糖の中で、β-1,4-マンノビオースがマウス骨髄樹状細胞を高レベルで活性化することが明らかになった。また、α型マンナンをβ-1,4-マンノビオースや他の多糖類と共に樹状細胞を刺激すると、樹状細胞による抗炎症サイトカイン産生が増強されることを見いだした。αマンノオリゴ糖に関しては、α-1,2およびα-1,6結合への伸長方向が任意に制御可能な保護基の組み合わせによるαマンノオリゴ糖の合成ルート構築を実施した。この目的を満たす共通中間体の最適化を行い、中間体を使用することによりそれぞれのα-1,2およびα-1,6結合型の直鎖オリゴ糖をベンジルグリコシド体として調製するルート構築に成功した。マンノシル化アレルゲンを発現する麹菌に関しては、オボアルブミン(OVA:モデルアレルゲン)の cDNAを麹菌グルコアミラーゼglaAの触媒ドメインをコードするDNAの下流に連結し、GlaA-OVA融合タンパク質として麹菌で発現させた。2日間液体培養した培養上清500 µL分をSDS-PAGEに供し、Coomassie Brilliant Blue R-250染色したところ、OVAの発現が確認できたが発現量は低かった。
  • 日本学術振興会:科学研究費助成事業 基盤研究(B)
    研究期間 : 2018年04月 -2021年03月 
    代表者 : 森 春英, 佐分利 亘
     
    糖質は構成糖と結合様式により顕著な多様性を示す.食品機能性素材やバイオ素材等,素材の潜在的宝箱であり,機能発見と応用利用に向けて,多様性に対応可能な効率的合成手法の確立が必須である.本申請研究は,合成酵素と転移酵素利用を利用した糖質多様化に向けた合成手法の確立を目的としている. 合成酵素利用による糖質合成に関しては,ショ糖からの糖ヌクレオチド合成酵素の高機能化に向けた変異酵素等の解析,および安定的な利用条件について検討を行った.糖供与体基質としてショ糖に依存しない糖ヌクレオチド合成酵素について,利用条件の検討を進めた.本酵素単独での反応による新規オリゴ糖数種の合成も行い,構造決定により新規化合物であることを確認した.反応条件検討により収率向上を図った. 糖転移酵素関連では,TS酵素(N末端側を伸長型酵素)は伸長部分を含めて主要3ドメインにより構成され,各ドメイン単独のタンパク質,ならびに各ドメイン欠失タンパク質を調製・機能解析を行い,各ドメインが有する機能を実験的に明らかにした.マルトオリゴ糖からイソマルトオリゴ糖形成に至る逐次的反応を明らかにした. 糖質の合成に関して,植物において代謝制御物質として機能するトレハロース6-リン酸を,酵素により合成する反応系を確立した.本反応では,マルトオリゴ糖を唯一の炭素源として,3酵素を含むワンポット反応により目的の糖リン酸を合成するものであり,簡便かつ有効な合成系である.
  • 日本学術振興会:科学研究費助成事業 基盤研究(C)
    研究期間 : 2018年04月 -2021年03月 
    代表者 : 佐分利 亘
     
    多様な構造を持つ糖質には様々な優良な機能が知られている。自然界に豊富に存在する糖質は極めて限定的で,豊富な糖質を希少糖質へと変換する技術を開発することで、新しい糖質の応用が拓けると考えられる.本研究では,単糖変換を触媒する異性化酵素であり,グルコースからマンノースへの一段階異性化反応を触媒するマンノース2-エピメラーゼ (ME) について機能・構造を解明すること,ホモログの機能解析を通じて新たな単糖変換酵素を取得することを目的とした。本年度は,MEに特徴的な長いループ構造に注目して3つの細菌に由来するMEホモログの機能を大腸菌組換え酵素を用いて解析し,いずれのホモログにもME活性を認めた。このことから,MEに特徴的な長いループ構造に着目することで精度良くMEを取得できることが示された.また,興味深いことに,これらの基質を検討する中で,ME酵素がキシロースやリキソースなどの単糖にも作用し,エピメラーゼ活性のみならずイソメラーゼ活性も微弱ながら示すことが明らかになった.Runella slithformis由来MEの高活性化変異酵素の取得に先立ち、変異酵素のハイスループットスクリーニング系を検討した。すなわち,96穴プレートを活用した小規模培養系による組換え酵素生産条件,溶菌試薬による酵素抽出条件と無細胞抽出液の酵素活性の評価方法を確立した。単糖にも有意に高いエピメリ化活性を持つMelioribacter roseus由来セロビオース2-エピメラーゼ (CE) について,本酵素に見られたMEに対応する長いループに注目し,この削除変異酵素を調製して基質特異性を検討した.当該変異酵素は野生型酵素より明らかに低い単糖に対する特異性を示した.ループの短縮化に伴う単糖特異性の低下から,本ループ構造がM. roseus由来CEの単糖への高い活性に重要なことが明らかになった。
  • 日本学術振興会:科学研究費助成事業 基盤研究(C)
    研究期間 : 2015年10月 -2018年03月 
    代表者 : 松井 博和, 佐分利 亘
     
    植物ではシグナル物質の多くは配糖化により不活性化され,加水分解により活性化される.本研究ではツベロン酸(TA)配糖体 を加水分解するイネβ-グルコシダーゼTAGG2がサリチル酸グルコシド (SAG) にも高い活性を持つことに注目し,SAG分解に重要なアミノ酸残基を特定し,アポプラストへの局在を明らかにした.TAGG2過剰発現イネではTA量の増加は見られたが,SA量の明確な増加は見られなかった.いもち菌接種試験では,TAGG過剰発現体において野生型よりも病斑形成が促進されることが明らかになった.シロイヌナズナホモログはSAGよりもラミナリオリゴ糖などオリゴ糖基質によく作用した.
  • 日本学術振興会:科学研究費助成事業 基盤研究(B)
    研究期間 : 2015年04月 -2018年03月 
    代表者 : 森 春英, 佐分利 亘
     
    糖質は,構成単糖と結合様式と重合度によって顕著な多様性を持つ分子群である.有用化合物が多数存在すると予想されるが,機能性の解析には潤沢な化合物が必要であり,効率的な大量合成系確立が必須である.本研究では,天然に豊富に存在する糖質からの転換として,合成酵素と転移酵素を利用した高度な糖質合成系確立を実施した.合成酵素利用では,ショ糖を出発物質として合成酵素の基質(UDP-Glcなどの糖ヌクレオチド)を供給するワンポット反応により二糖の合成系を確立した.新規転移酵素はマルトオリゴ糖に作用し,グルコース単位での転移反応を触媒する酵素群を見いだした.
  • 日本学術振興会:科学研究費助成事業 若手研究(B)
    研究期間 : 2014年04月 -2016年03月 
    代表者 : 佐分利 亘
     
    セロビオース2-エピメラーゼ (CE) は,β1-4二糖の還元末端グルコース残基をマンノース残基に異性化する。本酵素は触媒ドメインおよび触媒部位構造を他の単糖異性化酵素と共有する。本研究では,これら酵素の構造機能相関を解析した。Rhodothermus marinus由来CEの基質結合部位残基への変異により二糖特異性に重要なアミノ酸残基を決定した。また,本酵素に僅かなイソメラーゼ活性を認め,Cardicellulosiruptor saccharolyticus由来酵素との比較からイソメラーゼ活性に重要な構造を見出した。機能未知タンパク質の解析から、新規なマンノース異性化酵素を見出した。
  • オリゴ糖異性化酵素とその類縁酵素の構造基盤の解明
    文部科学省:科学研究費補助金 若手研究(B)
    研究期間 : 2014年04月 -2016年03月 
    代表者 : 佐分利 亘
  • 日本学術振興会:科学研究費助成事業 基盤研究(C)
    研究期間 : 2012年04月 -2015年03月 
    代表者 : 松井 博和, 佐分 利亘, 松浦 英幸
     
    ジャスモン酸 (JA) は病傷害ストレス応答,生長などに関与する植物ホルモンである.本研究ではJAシグナルの不活性化に働くと推定したCYP94D1,CYP94D2およびILL6の機能解析を行った.CYP94D1については遺伝子発現量の調整により表現型の変化が認められた.すなわち,遺伝子欠損株ではJAへの感受性の低下,過剰発現体ではJAの水酸化物の誘導体ツベロン酸グルコシドの蓄積が見られた.
  • オリゴ糖異性化酵素ならびに類縁酵素群の機能解明と有用糖質の効率合成への応用展開
    野田産業科学研究所:奨励研究助成
    研究期間 : 2014年04月 -2015年03月 
    代表者 : 佐分利 亘
  • 日本学術振興会:科学研究費助成事業 若手研究(B)
    研究期間 : 2012年04月 -2014年03月 
    代表者 : 佐分利 亘
     
    反芻動物の第一胃ルーメンに共生する偏性嫌気性細菌Ruminococcus albusは二つのマンノシルグルコースホスホリラーゼ (I型酵素とII型酵素) を持つ。基質特異性を検討したところ,I型酵素はマンノシルグルコースに特異的な酵素であり,II型酵素はマンノオリゴ糖に高い活性を示す酵素であることが判明した.合成反応では,I型酵素のみ6-OHグルコース誘導体をアクセプタ基質とした.アミノ酸配列の比較から推定したアミノ酸残基の変異酵素の解析から,I型酵素のAsp129が触媒残基と考えられた.また,I型酵素のIle212がグルコース6位誘導体への合成活性に重要な残基であることが明らかになった.
  • プレバイオティクスとして機能するエピラクトースの実用的合成法の開発
    科学技術振興機構:A-STEP 研究成果最適展開支援プログラム 第1回【FS】 探索タイプ
    研究期間 : 2013年08月 -2014年03月 
    代表者 : 佐分利 亘
  • 2つの新規な糖質ホスホリラーゼの分子解析
    文部科学省:科学研究費補助金 若手研究(B)
    研究期間 : 2012年04月 -2014年03月 
    代表者 : 佐分利 亘
  • プレバイオティクスの革新的酵素合成技術の開発
    ノーステック財団:研究開発助成事業」(フードイノベーション創造支援事業 研究シーズ発掘補助金)
    研究期間 : 2012年08月 -2013年03月 
    代表者 : 佐分利 亘
  • バイオリアクターを利用したエピラクトースの効率的合成法の開発
    ノーステック財団:「研究開発助成事業」(若手研究人材育成事業 Talent補助金)
    研究期間 : 2011年09月 -2012年03月 
    代表者 : 佐分利 亘
  • ルーメン細菌によるヘミセルロース分解の分子機構の解析
    公益財団法人秋山記念生命科学振興財団:研究助成 (奨励助成)
    研究期間 : 2011年04月 -2012年03月 
    代表者 : 佐分利 亘

産業財産権



Copyright © MEDIA FUSION Co.,Ltd. All rights reserved.