Researcher basic information

• 博士（農学）, 東京大学

• https://researchmap.jp/_hori?lang=en

• https://orcid.org/0000-0002-5740-153X
• https://jglobal.jst.go.jp/detail?JGLOBAL_ID=201601020460545298
• https://www.ees.hokudai.ac.jp

• https://orcid.org/0000-0002-5740-153X

• 201601020460545298

• Omics analyses
• CAZy
• Filamentous fungi
• Plant cell wall
• Wood decay fungi

• Bachelor's degree program, School of Science
• Master's degree program, Graduate School of Environmental Science
• Doctoral (PhD) degree program, Graduate School of Environmental Science

Research activity information

• Mar. 2024, 加藤記念バイオサイエンス振興財団, 研究助成・バイオテクノロジー分野
• Apr. 2022, 旭硝子財団, 研究奨励賞
• Mar. 2021, 日本農芸化学会, 若手女性研究者賞
  バイオマス分解利用に関する基礎研究
• Jun. 2020, 天野エンザイム科学技術振興財団, 酵素応用シンポジウム研究奨励賞
  堀 千明
• Mar. 2020, 日本木材学会, 奨励賞
  堀 千明
• Nov. 2018, Novozymes Japan, Research Fund 2018
  堀 千明
• Jun. 2018, 秋山記念生命科学振興財団, 奨励賞
  堀 千明
• Dec. 2013, 理化学研究所 環境資源科学研究センター, リトリート ポスター賞
  堀 千明
• Apr. 2013, 日本学術振興会, 特別研究員（PD）
  堀 千明
• Mar. 2013, US Department of Agriculture・Forest Products Laboratory, Certificate of application
  堀 千明
• Apr. 2011, 日本学術振興会, 特別研究員（DC２）
  堀 千明
• Aug. 2007, 日本木材学会, 優秀ポスター賞
  堀 千明

• Multi-proteomics reveals integrated metabolic and regulatory networks for xylan catabolism in Streptomyces sp. SirexAA-E.
  Tatsuya Nagano; Keisuke Ohashi; Petra Banko; Vijay Kumar; Chiaki Hori; Brian G Fox; Taichi E Takasuka
  Microbiology spectrum, e0225125, 20 Nov. 2025, [International Magazine]
  English, Scientific journal, An insect-associated bacterium, Streptomyces sp. SirexAA-E (SirexAA-E) secretes plant biomass-degrading enzymes depending on the available cell wall materials. SirexAA-E readily utilizes xylan, one of the major hemicelluloses. However, the enzyme composition and pathways supporting xylan metabolism in SirexAA-E and other Streptomycetes have not been reported. We aimed to understand changes in both extracellular and intracellular protein productions by cultivating SirexAA-E in defined media containing either xylose, xylobiose, or xylan. Proteomics showed each carbon source gave specific extracellular protein composition when compared to glucose. Furthermore, intracellular proteomics using a pair-wise Tandem Mass Tag (TMT)-labeling LC-MS/MS identified 1,037 proteins with changes in the xylose-, xylobiose-, or xylan-dependent proteome relative to the glucose-derived proteome. We found that numerous proteins related to oxidative phosphorylation were enriched in the pentose-grown proteomes relative to the glucose proteome. This observation is consistent with a high demand for ATP to support protein secretion and intake of xylose and xylooligosaccharides. Additionally, several transporters for carbon uptake were identified in the genome of SirexAA-E by protein homology comparison with Streptomyces coelicolor, and several key transcriptional regulators used by SirexAA-E for catabolizing xylan were found by pull-down proteomics. The current study provides new insights into the extensive extracellular and intracellular responses of a cellulolytic Streptomyces to the major plant hemicellulose.IMPORTANCEStreptomyces sp. SirexAA-E can efficiently degrade cellulose, xylan, and mannan, the major polysaccharide components of woody biomass. Our previous work showed the relative simplicity of the secreted proteome used to degrade cellulose. In this study, we report on the extracellular and intracellular proteomic responses of SirexAA-E during growth on xylan. The substrate-specific proteomic profiles have given a new understanding of the regulation of xylanolytic enzymes and additional metabolic pathways supporting growth on a pentose sugar. These groupings of regulatory and structural proteins provide a blueprint for construction of more robust strains for biomass valorization.
• Establishment of an antimetabolite-based transformation system for the wood-decaying basidiomycete Phanerochaete chrysosporium.
  Kazuma Masumoto; Petra Banko; Ayane Yamamoto; Kyoko Miwa; Chiaki Hori
  Applied and environmental microbiology, e0116025, 04 Sep. 2025, [International Magazine]
  English, Scientific journal, The model wood-decaying basidiomycete Phanerochaete chrysosporium has been extensively studied to elucidate the molecular mechanisms of wood decomposition. However, genetic studies have been limited by the lack of adequate genetic tools. Here, we established an antimetabolite-based transformation system, originally developed for ascomycetes, for use in P. chrysosporium. The transformation system utilizes pyrithiamine (PT), a thiamine antimetabolite, in combination with the pPTRII vector that contains the PT resistance gene (ptrA). PT effectively inhibited the growth of P. chrysosporium, and the introduction of ptrA conferred resistance to transformant mycelia. The transformation efficiency was comparable to that in ascomycetes, suggesting that the transformation system is also applicable to basidiomycetes. To examine the suitability of the system for heterologous gene expression, four cassettes were constructed to express GFP under the promoters of the actin1, DED, and GAPDH genes. Promoter activities were assessed via fluorescent microscopy observation of transformant mycelia and GFP quantification in crude cell extracts, revealing that the actin1 promoter drove the highest level of expression. Furthermore, truncating repeat sequences of the autonomously replicating sequence in the vector backbone improved transformation efficiency, likely due to the reduction in vector size. The transformation efficiency of the gene cassette-inserted vector in P. chrysosporium was relatively higher than that reported with alternative transformation systems in other species of wood-decaying basidiomycetes. The present transformation system could provide a platform for protein expression and genetic engineering in P. chrysosporium.IMPORTANCEWood-decaying basidiomycetes are well-recognized for their exceptional capabilities to decompose lignocellulosic biomass and oxidize a broad range of complex organic compounds. These capabilities are essential for maintaining the forest ecosystem and hold potential in biotechnological applications such as transforming recalcitrant biomass into useful compounds and degrading toxic substances in industrial effluents. However, genetic manipulation in basidiomycetes remains challenging because of the inefficiency of transformation systems. In the model lignocellulose-degrading basidiomycete, P. chrysosporium, transformation methods using dominant markers are scarce and were reported over two decades ago, necessitating the re-establishment of a functional system compatible with modern genetic tools like genome editing technology. In this study, an efficient genetic transformation system was achieved by using an antimetabolite-based selection strategy for P. chrysosporium. This transformation system would lay the foundation for advancing our understanding of the molecular mechanisms of wood decomposition and support the targeted optimization of basidiomycetes for various biotechnological applications.
• Identification and characterization of methoxy- and dimethoxyhydroquinone 1,2-dioxygenase from Phanerochaete chrysosporium.
  Hiroyuki Kato; Yasushi Takahashi; Hiromitsu Suzuki; Keisuke Ohashi; Ryunosuke Kawashima; Koki Nakamura; Kiyota Sakai; Chiaki Hori; Taichi E Takasuka; Masashi Kato; Motoyuki Shimizu
  Applied and environmental microbiology, e0175323, 23 Jan. 2024, [International Magazine]
  English, Scientific journal, White-rot fungi, such as Phanerochaete chrysosporium, are the most efficient degraders of lignin, a major component of plant biomass. Enzymes produced by these fungi, such as lignin peroxidases and manganese peroxidases, break down lignin polymers into various aromatic compounds based on guaiacyl, syringyl, and hydroxyphenyl units. These intermediates are further degraded, and the aromatic ring is cleaved by 1,2,4-trihydroxybenzene dioxygenases. This study aimed to characterize homogentisate dioxygenase (HGD)-like proteins from P. chrysosporium that are strongly induced by the G-unit fragment of vanillin. We overexpressed two homologous recombinant HGDs, PcHGD1 and PcHGD2, in Escherichia coli. Both PcHGD1 and PcHGD2 catalyzed the ring cleavage in methoxyhydroquinone (MHQ) and dimethoxyhydroquinone (DMHQ). The two enzymes had the highest catalytic efficiency (kcat/Km) for MHQ, and therefore, we named PcHGD1 and PcHGD2 as MHQ dioxygenases 1 and 2 (PcMHQD1 and PcMHQD2), respectively, from P. chrysosporium. This is the first study to identify and characterize MHQ and DMHQ dioxygenase activities in members of the HGD superfamily. These findings highlight the unique and broad substrate spectra of PcHGDs, rendering them attractive candidates for biotechnological applications.IMPORTANCEThis study aimed to elucidate the properties of enzymes responsible for degrading lignin, a dominant natural polymer in terrestrial lignocellulosic biomass. We focused on two homogentisate dioxygenase (HGD) homologs from the white-rot fungus, P. chrysosporium, and investigated their roles in the degradation of lignin-derived aromatic compounds. In the P. chrysosporium genome database, PcMHQD1 and PcMHQD2 were annotated as HGDs that could cleave the aromatic rings of methoxyhydroquinone (MHQ) and dimethoxyhydroquinone (DMHQ) with a preference for MHQ. These findings suggest that MHQD1 and/or MHQD2 play important roles in the degradation of lignin-derived aromatic compounds by P. chrysosporium. The preference of PcMHQDs for MHQ and DMHQ not only highlights their potential for biotechnological applications but also underscores their critical role in understanding lignin degradation by a representative of white-rot fungus, P. chrysosporium.
• Basic Researches toward Plant Biomass Utilization: Elucidation of Various Lignocellulose Degradation Systems by Wood Decay Fungi and Modification of Xylem Formation in Tree
  堀千明
  化学と生物, 61, 12, 590, 595, Dec. 2023, [Peer-reviewed], [Invited]
• Genomic and Secretomic Analyses of the Newly Isolated Fungus Perenniporia fraxinea SS3 Identified CAZymes Potentially Related to a Serious Pathogenesis of Hardwood Trees.
  Ruy Matsumoto; Jakia Jerin Mehjabin; Hideki Noguchi; Toshizumi Miyamoto; Taichi E Takasuka; Chiaki Hori
  Applied and environmental microbiology, e0027223, 26 Apr. 2023, [International Magazine]
  English, Scientific journal, Perenniporia fraxinea can colonize living trees and cause severe damage to standing hardwoods by secreting a number of carbohydrate-activate enzymes (CAZymes), unlike other well-studied Polyporales. However, significant knowledge gaps exist in understanding the detailed mechanisms for this hardwood-pathogenic fungus. To address this issue, five monokaryotic P. fraxinea strains, SS1 to SS5, were isolated from the tree species Robinia pseudoacacia, and high polysaccharide-degrading activities and the fastest growth were found for P. fraxinea SS3 among the isolates. The whole genome of P. fraxinea SS3 was sequenced, and its unique CAZyme potential for tree pathogenicity was determined in comparison to the genomes of other nonpathogenic Polyporales. These CAZyme features are well conserved in a distantly related tree pathogen, Heterobasidion annosum. Furthermore, the carbon source-dependent CAZyme secretions of P. fraxinea SS3 and a nonpathogenic and strong white-rot Polyporales member, Phanerochaete chrysosporium RP78, were compared by activity measurements and proteomic analyses. As seen in the genome comparisons, P. fraxinea SS3 exhibited higher pectin-degrading activities and higher laccase activities than P. chrysosporium RP78, which were attributed to the secretion of abundant glycoside hydrolase family 28 (GH28) pectinases and auxiliary activity family 1_1 (AA1_1) laccases, respectively. These enzymes are possibly related to fungal invasion into the tree lumens and the detoxification of tree defense substances. Additionally, P. fraxinea SS3 showed secondary cell wall degradation capabilities at the same level as that of P. chrysosporium RP78. Overall, this study suggested mechanisms for how this fungus can attack the cell walls of living trees as a serious pathogen and differs from other nonpathogenic white-rot fungi. IMPORTANCE Many studies have been done to understand the mechanisms underlying the degradation of plant cell walls of dead trees by wood decay fungi. However, little is known about how some of these fungi weaken living trees as pathogens. P. fraxinea belongs to the Polyporales, a group of strong wood decayers, and is known to aggressively attack and fell standing hardwood trees all over the world. Here, we report CAZymes potentially related to plant cell wall degradation and pathogenesis factors in a newly isolated fungus, P. fraxinea SS3, by genome sequencing in conjunction with comparative genomic and secretomic analyses. The present study provides insights into the mechanisms of the degradation of standing hardwood trees by the tree pathogen, which will contribute to the prevention of this serious tree disease.
• Enhancement of Secondary Cell Wall Formation in Poplar Xylem Using a Self-Reinforced System of Secondary Cell Wall-Related Transcription Factors.
  Yoshimi Nakano; Hitoshi Endo; Lorenz Gerber; Chiaki Hori; Ayumi Ihara; Masayo Sekimoto; Tomoko Matsumoto; Jun Kikuchi; Misato Ohtani; Taku Demura
  Frontiers in plant science, 13, 819360, 819360, 2022, [International Magazine]
  English, Scientific journal, The secondary cell wall (SCW) in the xylem is one of the largest sink organs of carbon in woody plants, and is considered a promising sustainable bioresource for biofuels and biomaterials. To enhance SCW formation in poplar (Populus sp.) xylem, we developed a self-reinforced system of SCW-related transcription factors from Arabidopsis thaliana, involving VASCULAR-RELATED NAC-DOMAIN7 (VND7), SECONDARY WALL-ASSOCIATED NAC-DOMAIN PROTEIN 1/NAC SECONDARY WALL THICKENING-PROMOTING FACTOR3 (SND1/NST3), and MYB46. In this system, these transcription factors were fused with the transactivation domain VP16 and expressed under the control of the Populus trichocarpa CesA18 (PtCesA18) gene promoter, creating the chimeric genes PtCesA18pro::AtVND7:VP16, PtCesA18pro::AtSND1:VP16, and PtCesA18pro::AtMYB46:VP16. The PtCesA18 promoter is active in tissues generating SCWs, and can be regulated by AtVND7, AtSND1, and AtMYB46; thus, the expression levels of PtCesA18pro::AtVND7:VP16, PtCesA18pro::AtSND1:VP16, and PtCesA18pro::AtMYB46:VP16 are expected to be boosted in SCW-generating tissues. In the transgenic hybrid aspens (Populus tremula × tremuloides T89) expressing PtCesA18pro::AtSND1:VP16 or PtCesA18pro::AtMYB46:VP16 grown in sterile half-strength Murashige and Skoog growth medium, SCW thickening was significantly enhanced in the secondary xylem cells, while the PtCesA18pro::AtVND7:VP16 plants showed stunted xylem formation, possibly because of the enhanced programmed cell death (PCD) in the xylem regions. After acclimation, the transgenic plants were transferred from the sterile growth medium to pots of soil in the greenhouse, where only the PtCesA18pro::AtMYB46:VP16 aspens survived. A nuclear magnetic resonance footprinting cell wall analysis and enzymatic saccharification analysis demonstrated that PtCesA18pro::AtMYB46:VP16 influences cell wall properties such as the ratio of syringyl (S) and guaiacyl (G) units of lignin, the abundance of the lignin β-aryl ether and resinol bonds, and hemicellulose acetylation levels. Together, these data indicate that we have created a self-reinforced system using SCW-related transcription factors to enhance SCW accumulation.
• Omics analyses and biochemical study of Phlebiopsis gigantea elucidate its degradation strategy of wood extractives.
  Mana Iwata; Ana Gutiérrez; Gisela Marques; Grzegorz Sabat; Philip J Kersten; Daniel Cullen; Jennifer M Bhatnagar; Jagjit Yadav; Anna Lipzen; Yuko Yoshinaga; Aditi Sharma; Catherine Adam; Christopher Daum; Vivian Ng; Igor V Grigoriev; Chiaki Hori
  Scientific reports, 11, 1, 12528, 12528, 15 Jun. 2021, [International Magazine]
  English, Scientific journal, Wood extractives, solvent-soluble fractions of woody biomass, are considered to be a factor impeding or excluding fungal colonization on the freshly harvested conifers. Among wood decay fungi, the basidiomycete Phlebiopsis gigantea has evolved a unique enzyme system to efficiently transform or degrade conifer extractives but little is known about the mechanism(s). In this study, to clarify the mechanism(s) of softwood degradation, we examined the transcriptome, proteome, and metabolome of P. gigantea when grown on defined media containing microcrystalline cellulose and pine sapwood extractives. Beyond the conventional enzymes often associated with cellulose, hemicellulose and lignin degradation, an array of enzymes implicated in the metabolism of softwood lipophilic extractives such as fatty and resin acids, steroids and glycerides was significantly up-regulated. Among these, a highly expressed and inducible lipase is likely responsible for lipophilic extractive degradation, based on its extracellular location and our characterization of the recombinant enzyme. Our results provide insight into physiological roles of extractives in the interaction between wood and fungi.
• Transport-coupled ubiquitination of the borate transporter BOR1 for its boron-dependent degradation.
  Akira Yoshinari; Takuya Hosokawa; Marcel Pascal Beier; Keishi Oshima; Yuka Ogino; Chiaki Hori; Taichi E Takasuka; Yoichiro Fukao; Toru Fujiwara; Junpei Takano
  The Plant cell, 33, 2, 420, 438, 17 Apr. 2021, [International Magazine]
  English, Scientific journal, Plants take up and translocate nutrients through transporters. In Arabidopsis thaliana, the borate exporter BOR1 acts as a key transporter under boron (B) limitation in the soil. Upon sufficient-B supply, BOR1 undergoes ubiquitination and is transported to the vacuole for degradation, to avoid overaccumulation of B. However, the mechanisms underlying B-sensing and ubiquitination of BOR1 are unknown. In this study, we confirmed the lysine-590 residue in the C-terminal cytosolic region of BOR1 as the direct ubiquitination site and showed that BOR1 undergoes K63-linked polyubiquitination. A forward genetic screen identified that amino acid residues located in vicinity of the substrate-binding pocket of BOR1 are essential for the vacuolar sorting. BOR1 variants that lack B-transport activity showed a significant reduction of polyubiquitination and subsequent vacuolar sorting. Coexpression of wild-type (WT) and a transport-defective variant of BOR1 in the same cells showed degradation of the WT but not the variant upon sufficient-B supply. These findings suggest that polyubiquitination of BOR1 relies on its conformational transition during the transport cycle. We propose a model in which BOR1, as a B transceptor, directly senses the B concentration and promotes its own polyubiquitination and vacuolar sorting for quick and precise maintenance of B homeostasis.
• Identifying transcription factors that reduce wood recalcitrance and improve enzymatic degradation of xylem cell wall in Populus
  Chiaki Hori; Naoki Takata; Pui Ying Lam; Yuki Tobimatsu; Soichiro Nagano; Jenny C. Mortimer; Dan Cullen
  Scientific Reports, 10, 1, 22043, 22043, Springer Science and Business Media LLC, 16 Dec. 2020, [Peer-reviewed], [Lead author, Corresponding author], [International Magazine]
  English, Scientific journal, Developing an efficient deconstruction step of woody biomass for biorefinery has been drawing considerable attention since its xylem cell walls display highly recalcitrance nature. Here, we explored transcriptional factors (TFs) that reduce wood recalcitrance and improve saccharification efficiency in Populus species. First, 33 TF genes up-regulated during poplar wood formation were selected as potential regulators of xylem cell wall structure. The transgenic hybrid aspens (Populus tremula × Populus tremuloides) overexpressing each selected TF gene were screened for in vitro enzymatic saccharification. Of these, four transgenic seedlings overexpressing previously uncharacterized TF genes increased total glucan hydrolysis on average compared to control. The best performing lines overexpressing Pt × tERF123 and Pt × tZHD14 were further grown to form mature xylem in the greenhouse. Notably, the xylem cell walls exhibited significantly increased total xylan hydrolysis as well as initial hydrolysis rates of glucan. The increased saccharification of Pt × tERF123-overexpressing lines could reflect the improved balance of cell wall components, i.e., high cellulose and low xylan and lignin content, which could be caused by upregulation of cellulose synthase genes upon the expression of Pt × tERF123. Overall, we successfully identified Pt × tERF123 and Pt × tZHD14 as effective targets for reducing cell wall recalcitrance and improving the enzymatic degradation of woody plant biomass.
• Impact of abiotic stress on the regulation of cell wall biosynthesis in Populus trichocarpa.
  Chiaki Hori; Xiang Yu; Jenny C Mortimer; Ryosuke Sano; Tomoko Matsumoto; Jun Kikuchi; Taku Demura; Misato Ohtani
  Plant biotechnology (Tokyo, Japan), 37, 3, 273, 283, 25 Sep. 2020, [Domestic magazines]
  English, Scientific journal, Growth of biomass for lignocellulosic biofuels and biomaterials may take place on land unsuitable for foods, meaning the biomass plants are exposed to increased abiotic stresses. Thus, the understanding how this affects biomass composition and quality is important for downstream bioprocessing. Here, we analyzed the effect of drought and salt stress on cell wall biosynthesis in young shoots and xylem tissues of Populus trichocarpa using transcriptomic and biochemical methods. Following exposure to abiotic stress, stem tissues reduced vessel sizes, and young shoots increased xylem formation. Compositional analyses revealed a reduction in the total amount of cell wall polysaccharides. In contrast, the total lignin amount was unchanged, while the ratio of S/G lignin was significantly decreased in young shoots. Consistent with these observations, transcriptome analyses show that the expression of a subset of cell wall-related genes is tightly regulated by drought and salt stresses. In particular, the expression of a part of genes encoding key enzymes for S-lignin biosynthesis, caffeic acid O-methyltransferase and ferulate 5-hydroxylase, was decreased, suggesting the lower S/G ratio could be partly attributed to the down-regulation of these genes. Together, our data identifies a transcriptional abiotic stress response strategy in poplar, which results in adaptive changes to the plant cell wall.
• Isolation of poly[D-lactate (LA)-co-3-hydroxybutyrate)]-degrading bacteria from soil and characterization of D-LA homo-oligomer degradation by the isolated strains
  Chiaki Hori; Tomohiro Sugiyama; Kodai Watanabe; Jian Sun; Yuu Kamada; Toshihiko Ooi; Takuya Isono; Toshifumi Satoh; Shin-ichiro Sato; Seiichi Taguchi; Ken'ichiro Matsumoto
  POLYMER DEGRADATION AND STABILITY, 179, 109231, 109231, Sep. 2020, [Peer-reviewed], [Lead author]
  English, Scientific journal
• Proteomic Characterization of Lignocellulolytic Enzymes Secreted by the Insect-Associated Fungus Daldinia decipiens oita, Isolated from a Forest in Northern Japan
  Chiaki Hori; Ruopu Song; Kazuki Matsumoto; Ruy Matsumoto; Benjamin B. Minkoff; Shuzo Oita; Hideho Hara; Taichi E. Takasuka
  APPLIED AND ENVIRONMENTAL MICROBIOLOGY, 86, 8, Apr. 2020, [Peer-reviewed], [Lead author, Corresponding author], [International Magazine]
  English, Scientific journal
• Synergy of valine and threonine supplementation on poly(2-hydroxybutyrate-block-3-hydroxybutyrate) synthesis in engineered Escherichia coli expressing chimeric polyhydroxyalkanoate synthase.
  Maho Sudo; Chiaki Hori; Toshihiko Ooi; Shoji Mizuno; Takeharu Tsuge; Ken'ichiro Matsumoto
  Journal of bioscience and bioengineering, 129, 3, 302, 306, 18 Oct. 2019, [Peer-reviewed], [Domestic magazines]
  English, Scientific journal, The engineered chimeric polyhydroxyalkanoate (PHA) synthase PhaCAR is composed of N-terminal portion of Aeromonas caviae PHA synthase and C-terminal portion of Ralstonia eutropha (Cupriavidus necator) PHA synthase. PhaCAR has a unique and useful capacity to synthesize the block PHA copolymer poly(2-hydroxybutyrate-block-3-hydroxybutyrate) [P(2HB-b-3HB)] in engineered Escherichia coli from exogenous 2HB and 3HB. In the present study, we initially attempted to incorporate the amino acid-derived 2-hydroxyalkanoate (2HA) units using PhaCAR and the 2HA-CoA-supplying enzymes lactate dehydrogenase (LdhA) and CoA transferase (HadA). Cells harboring the genes for PhaCAR, LdhA, and HadA, as well as for the 3HB-CoA-supplying enzymes β-ketothiolase and acetoacetyl-CoA reductase, were cultivated with supplementation of four hydrophobic amino acids, i.e., leucine, valine (Val), isoleucine (Ile), and phenylalanine, in the medium. No hydrophobic amino acid-derived monomers were incorporated into the polymer, which was most likely because of the strict substrate specificity of PhaCAR; however, P(2HB-co-3HB) was unexpectedly produced with Val supplementation. The copolymer was likely P(2HB-b-3HB) based on proton nuclear magnetic resonance analysis. Based on the endogenous pathways in E. coli, 2HB units are likely derived from threonine (Thr) through deamination and dihydroxylation. In fact, dual supplementation with Thr and Val showed synergy on the 2HB fraction of the polymer. Val supplementation promoted the 2HB synthesis likely by inhibiting the metabolism of 2-ketobutyrate into Ile and/or activating Thr dehydratase. In conclusion, the LdhA/HadA/PhaCAR pathway served as the system for the synthesis of P(2HB-b-3HB) from biomass-derived carbon sources.
• Genome Sequence of Striga asiatica Provides Insight into the Evolution of Plant Parasitism
  Satoko Yoshida; Seungill Kim; Eric K. Wafula; Jaakko Tanskanen; Yong-Min Kim; Loren Honaas; Zhenzhen Yang; Thomas Spallek; Caitlin E. Conn; Yasunori Ichihashi; Kyeongchae Cheong; Songkui Cui; Joshua P. Der; Heidrun Gundlach; Yuannian Jiao; Chiaki Hori; Juliane K. Ishida; Hiroyuki Kasahara; Takatoshi Kiba; Myung-Shin Kim; Namjin Koo; Anuphon Laohavisit; Yong-Hwan Lee; Shelley Lumba; Peter McCourt; Jenny C. Mortimer; J. Musembi Mutuku; Takahito Nomura; Yuko Sasaki-Sekimoto; Yoshiya Seto; Yu Wang; Takanori Wakatake; Hitoshi Sakakibara; Taku Demura; Shinjiro Yamaguchi; Koichi Yoneyama; Ri-ichiroh Manabe; David C. Nelson; Alan H. Schulman; Michael P. Timko; Claude W. DePamphilis; Doil Choi; Ken Shirasu
  CURRENT BIOLOGY, 29, 18, 3041, +, Sep. 2019, [Peer-reviewed], [International Magazine]
  English, Scientific journal
• Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO)-mediated de novo synthesis of glycolate-based polyhydroxyalkanoate in Escherichia coli
  Ken'ichiro Matsumoto; Jun Saito; Toshinori Yokoo; Chiaki Hori; Akihiro Nagata; Yuki Kudoh; Toshihiko Ooi; Seiichi Taguchi
  JOURNAL OF BIOSCIENCE AND BIOENGINEERING, 128, 3, 302, 306, Sep. 2019, [Peer-reviewed]
  English, Scientific journal
• High-cell density culture of poly(lactate-co-3-hydroxybutyrate)-producing Escherichia coli by using glucose/xylose-switching fed-batch jar fermentation
  Chiaki Hori; Takashi Yamazaki; Greg Ribordy; Kenji Takisawa; Ken'ichiro Matsumoto; Toshihiko Ooi; Manfred Zinn; Seiichi Taguchi
  JOURNAL OF BIOSCIENCE AND BIOENGINEERING, 127, 6, 721, 725, Jun. 2019, [Peer-reviewed], [Lead author], [Domestic magazines]
  English, Scientific journal
• The Structural Integrity of Lignin Is Crucial for Resistance against Striga hermonthica Parasitism in Rice
  J. Musembi Mutuku; Songkui Cui; Chiaki Hori; Yuri Takeda; Yuki Tobimatsu; Ryo Nakabayashi; Tetsuya Mori; Kazuki Saito; Taku Demura; Toshiaki Umezawa; Satoko Yoshida; Ken Shirasu
  PLANT PHYSIOLOGY, 179, 4, 1796, 1809, Apr. 2019, [Peer-reviewed], [International Magazine]
  English, Scientific journal
• Genomes of Neutrophilic Sulfur-Oxidizing Chemolithoautotrophs Representing 9 Proteobacterial Species From 8 Genera
  Tomohiro Watanabe; Hisaya Kojima; Kazuhiro Umezawa; Chiaki Hori; Taichi E. Takasuka; Yukako Kato; Manabu Fukui
  FRONTIERS IN MICROBIOLOGY, 10, 316, Feb. 2019, [Peer-reviewed]
  English, Scientific journal
• Protein components of water extracts from fruiting bodies of the reishi mushroom Ganoderma lucidum contribute to the production of functional molecules
  Kei Kumakura; Chiaki Hori; Hiroki Matsuoka; Kiyohiko Igarashi; Masahiro Samejima
  JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, 99, 2, 529, 535, Jan. 2019, [Peer-reviewed], [Lead author]
  English, Scientific journal
• Origin and Diversity of Wood Decay Fungi Revealed by Genome-Based Analyses
  Chiaki Hori; Makoto Yoshida; Kiyohiko Igarashi; Masahiro Samejima
  J. Jpn. Wood Sci. Soc., 65, 4, 173, 188, 2019, [Peer-reviewed], [Lead author]
  Japanese
• Secretome analysis of the basidiomycete Phanerochaete chrysosporium grown on ammonia-treated lignocellulosic biomass from birch wood
  Kiyoshi Sakuragi; Chiaki Hori; Kiyohiko Igarashi; Masahiro Samejima
  JOURNAL OF WOOD SCIENCE, 64, 6, 845, 853, Dec. 2018, [Peer-reviewed]
  English, Scientific journal
• Multi-omit Analyses of Extensively Decayed Pinus contorta Reveal Expression of a Diverse Array of Lignocellulose-Degrading Enzymes
  Chiaki Hori; Jill Gaskell; Dan Cullen; Grzegorz Sabat; Philip E. Stewart; Kathleen Lail; Yi Peng; Kerrie Barry; Igor V. Grigoriev; Annegret Kohler; Laure Fauchery; Francis Martin; Carolyn A. Zeiner; Jennifer M. Bhatnagar
  APPLIED AND ENVIRONMENTAL MICROBIOLOGY, 84, 20, Oct. 2018, [Peer-reviewed]
  English, Scientific journal
• In Vitro Analysis of D-Lactyl-CoA-Polymerizing Polyhydroxyalkanoate Synthase in Polylactate and Poly(lactate-co-3-hydroxybutyrate) Syntheses
  Ken'ichiro Matsumoto; Midori Iijima; Chiaki Hori; Camila Utsunomia; Toshihiko Ooi; Seiichi Taguchi
  BIOMACROMOLECULES, 19, 7, 2889, 2895, Jul. 2018, [Peer-reviewed]
  English, Scientific journal
• Site-directed saturation mutagenesis of polyhydroxylalkanoate synthase for efficient microbial production of poly, which is a polymer molecule composed of lactic acid (LA) and 3-hydroxybutanoic acid (3-HB). And the degradability by environmental microorganisms was evaluated.
  First, we investigated the microbial production method of lactic acid copolymer and established a culture method with controlled lactic acid content. The obtained copolymer were formed into a film to evaluate the degradation in the environment, and a phylogenetic analysis of the environmental microorganisms involved in the degradation was performed.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, Competitive research funding, 17K00619
• 植物バイオマス分解に関わる新規酵素の探索とその利用
  2018年度研究助成（推奨）
  Apr. 2018 - Mar. 2019
  堀 千明
  秋山記念生命科学振興財団, Principal investigator, Competitive research funding
• Exploration of the novel enzymes related to deconstruction of woody extractives by white-rot fungi
  Research Fund 2018
  Apr. 2018 - Mar. 2019
  堀 千明
  Novozymes Japan, Principal investigator, Competitive research funding
• 16K18727
  Grant-in-Aid for Young Scientists (B)
  Apr. 2016 - Mar. 2019
  Chiaki Hori
  Grants-in-Aid for Scientific Research(KAKEN), Principal investigator, Competitive research funding
• スーパーグローバル大学創成事業 SG FResHU Support
  Nov. 2018 - Nov. 2018
  堀 千明
  北海道大学, Principal investigator, Competitive research funding
• 若手研究者学会参加支援事業
  平成30年度 フロンティア化学教育研究センター
  Sep. 2018 - Sep. 2018
  堀 千明
  北海道大学, Principal investigator, Competitive research funding
• 木材腐朽菌による植物抽出物質の分解メカニズムの解明
  H29若手若手研究者フィージビリティ・スタディ支援事業
  Oct. 2017 - Mar. 2018
  堀 千明
  北海道大学FCC, Principal investigator, Competitive research funding
• 13J01143
  Grant-in-Aid for Postdoctoral JSPS Fellows
  Apr. 2013 - Mar. 2016
  Chiaki Hori
  本研究では、担子菌分解機構に関わる酵素群を植物改変のための遺伝子材料として利用することで、易分解性バイオマス生産植物の作出を目指す。植物細胞壁の分解性において重要なファクターになるキシランの構造を変化させるために、木粉培地で担子菌が多く生産したキシラン分解酵素を選択した。昨年度までに組換えポプラの細胞壁解析について終了していたため、本年度では得られた組換えポプラの細胞壁形成に与える影響について二次壁形成に関わる遺伝子の転写産物量の変化を測定することにより詳細な分子メカニズムを明らかにする予定であった。そこで、3種の変異株についてマイクロアレイ解析を行った。GH10の変異株においては２倍以上増加した遺伝子群についてGO解析をしたところ、細胞壁形成関連遺伝子群に変化がみられた。そこで、細胞壁形成関連遺伝子を抽出し、詳細な遺伝子発現変化を解析した。その結果、野生株と比較してリグニン合成に関わるいくつかのLaccase遺伝子の発現量が増加しており、これらが変異体の細胞壁形成の変化に関わっている可能性が考えられた。これら研究を通し、菌類由来のキシラン分解酵素を導入したポプラでは、単純にキシランが分解されたポプラが出来上がるのではなく、そのような変化をポプラは感知し細胞壁形成を分子レベルで変化させることを明らかにした。本研究の本来の目的である易分解性ポプラの作出には成功しなかったが、細胞壁構造を遺伝子工学的手法を用いて変化させる上で重要な知見が得られたと考えている。
  Grants-in-Aid for Scientific Research(KAKEN), 特別研究員奨励費, 国立研究開発法人理化学研究所, Principal investigator, Competitive research funding, 13J01143
• 11J03288
  Grant-in-Aid for Doctral JSPS Fellows
  Apr. 2011 - Mar. 2013
  Chiaki Hori
  本研究では、分解機構に新たな知見を与えるために、単一バイオマス成分を使用した新しいモデル系を取り入れ、セクレトーム解析およびRNAseqを利用したトランスクリプトーム解析にて観察することを目的としている。
  昨年度に、担子菌Phanerochaete chrysosporiumがセルロース培地にキシランを添加すると、初期成長速度が早くなるとともに、菌体外酵素生産が増加することを明らかにした。それらはキシラン分解関連酵素だけでなく、セルロースの酸化的分解に関与すると考えられるセロビオース脱水素酵素(CDH)および糖質加水分解酵素(GH)ファミリー61タンパク質の生産も促進されることが明らかとなった。
  そこで今年度では、キシラン添加時に観察された現象を引き起こす原因となるキシランの構造を明らかにすることを目的とした。キシランは、キシロースがβ-1,4結合した主鎖にアラビノースやグルクロン酸、アセチル基などの側鎖が付加されたヘテロ多糖である。側鎖構造の違うキシランを添加した培地で本菌を生育させ、菌体量や菌体外酵素を解析したところ、ほとんど同じ傾向の結果が得られたことから、主鎖構造が菌体に影響を与えたことが推測された。そこで、直鎖状のキシロオリゴ糖(重合度1-4)に対するCDHの遺伝子応答を定量PCR解析によって調べたところ、キシロースには反応しない一方でキシロオリゴ糖には顕著に反応した。しかしながら、それらの応答強度は対照として測定したセロオリゴ糖に対する遺伝子応答強度よりも著しく小さかった。そこで、セロオリゴ糖を生産する主要なセルラーゼ遺伝子についてもキシロオリゴ糖に対する遺伝子応答を観察したところ、一部のセルラーゼ遺伝子(Cel7C)が顕著に二量体以上のキシロオリゴ糖に顕著に反応する事が明らかとなった。これらの結果から、キシロオリゴ糖によって誘導生産された一部セルラーゼのセルロース分解によってセロオリゴ糖の生成が促され、このセロオリゴ糖によりセルロース分解関連酵素の遺伝子全体が連鎖的に強く発現誘導されるといった増強作用を持つカスケード的応答機構が存在する可能性を示した。
  そこで、キシロースおよび重合度2-4のキシロオリゴ糖に対するゲノムワイドな遺伝子応答を観察するために、Illuminaシーケンサーを用いて全転写産物解析を行った。糖質関連酵素遺伝子における発現応答を解析したところ、キシラン分解酵素よりも一部のセルロース分解関連酵素遺伝子が、キシロオリゴ糖に対する高い発現応答能をもつことが明らかとなり、上述したような応答機構の存在が強く示唆された。
  Grants-in-Aid for Scientific Research(KAKEN), 特別研究員奨励費, 東京大学, Principal investigator, Competitive research funding, 11J03288

• 担子菌由来のリパーゼによるポリエステルを分解する方法
  Patent right, 堀千明; 林 恭広; 境野 一馬
  特願2025‐37796, 10 Mar. 2025
• Use of novel highly functional lipase from Basidiomycetes
  Patent right, Chiaki Hori
  PCT/JP2022/6467, 17 Feb. 2022
• 担子菌由来の新規な高機能性リパーゼの利用
  Patent right, 堀千明, 北海道大学工学研究院
  特願2021-024557, Feb. 2021