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ASHIDA HirokiGraduate School of Human Development and Environment / Department of Human Environmental ScienceProfessor
Researcher basic information
■ Research news- 26 Mar. 2019, Why photosynthesis works better for some plants than others
- 31 Jan. 2017, Mechanism for photosynthesis already existed in primeval microbe
■ Research Areas
- Life sciences / Applied molecular and cellular biology
- Environmental science/Agricultural science / Landscape science
- Environmental science/Agricultural science / Environmental agriculture
- Life sciences / Evolutionary biology
- Life sciences / Molecular biology
- Life sciences / Plants: molecular biology and physiology
Research activity information
■ Award- Mar. 2015 日本農芸化学会, 農芸化学奨励賞, 光合成CO2固定酵素RuBisCOの機能進化研究Japan society
- May 2010 日本生化学会近畿支部, 優秀発表賞, RuBisCO-like proteinを用いた光合成CO2固定酵素RuBisCOの分子進化研究Japan society
- Glycogen serves as a metabolic sink in cyanobacteria. Glycogen deficiency causes the extracellular release of distinctive metabolites such as pyruvate and 2-oxoglutarate upon nitrogen depletion; however, the mechanism has not been fully elucidated. This study aimed to elucidate the mechanism of carbon partitioning in glycogen-deficient cyanobacteria. Extracellular and intracellular metabolites in a glycogen-deficient ΔglgC mutant of Synechococcus elongatus PCC 7942 were comprehensively analyzed. In the presence of a nitrogen source, the ΔglgC mutant released extracellular glutamate rather than pyruvate and 2-oxoglutarate, whereas its intracellular glutamate level was lower than that in the wild-type strain. The de novo synthesis of glutamate increased in the ΔglgC mutant, suggesting that glycogen deficiency enhanced carbon partitioning into glutamate and extracellular excretion through an unidentified transport system. This study proposes a model in which glutamate serves as the prime extracellular metabolic sink alternative to glycogen when nitrogen is available.Feb. 2024, Communications biology, 7(1) (1), 233 - 233, English, International magazineScientific journal
- Abstract The cyanobacterium Synechococcus elongatus PCC 7942 accumulates alarmone guanosine tetraphosphate (ppGpp) under stress conditions, such as darkness. A previous study observed that artificial ppGpp accumulation under photosynthetic conditions led to the downregulation of genes involved in the nitrogen assimilation system, which is activated by the global nitrogen regulator NtcA, suggesting that ppGpp regulates NtcA activity. However, the details of this mechanism have not been elucidated. Here, we investigate the metabolic responses associated with ppGpp accumulation by heterologous expression of the ppGpp synthetase RelQ. The pool size of 2-oxoglutarate (2-OG), which activates NtcA, is significantly decreased upon ppGpp accumulation. De novo 13C-labeled CO2 assimilation into the Calvin-Benson-Bassham cycle and glycolytic intermediates continues irrespective of ppGpp accumulation, whereas the labeling of 2-OG is significantly decreased under ppGpp accumulation. The low 2-OG levels in the RelQ overexpression cells could be because of the inhibition of metabolic enzymes, including aconitase, which are responsible for 2-OG biosynthesis. We propose a metabolic rearrangement by ppGpp accumulation, which negatively regulates 2-OG levels to maintain carbon and nitrogen balance.Springer Science and Business Media LLC, Dec. 2023, Communications Biology, 6(1) (1)Scientific journal
- Scope: Human thioredoxin-1 (hTrx-1) is a defensive protein induced by various stresses and exerts antioxidative and anti-inflammatory effects. Previously, we described a transplastomic lettuce overexpressing hTrx-1 that exerts a protective effect against oxidative damage in a pancreatic β-cell line. In this study, we treated diabetic mice (Akita mice) with exogenous hTrx-1 and evaluated the effects. Methods and results: Treatment with drinking water and single applications of exogenous hTrx-1 did not influence the feeding, drinking behavior, body weight, blood glucose, or glycosylated hemoglobin (HbA1c) levels in Akita mice. However, chronic administration of a 10% hTrx-1 lettuce-containing diet was associated with a significant reduction from the baseline of HbA1c levels compared with mice fed a wild-type lettuce-containing diet. It also resulted in an increased number of goblet cells in the small intestine, indicating that mucus was synthesized and secreted. Conclusion: Our results revealed that the administration of an hTrx-1 lettuce-containing diet improves the baseline level of HbA1c in Akita mice. This effect is mediated through goblet cell proliferation and possibly related to protection against postprandial hyperglycemia by mucus, which results in the improvement of blood glucose control. These findings suggest that the hTrx-1 lettuce may be a useful tool for the continuous antioxidative and antidiabetic efficacies of the hTrx-1 protein.Aug. 2021, Food science & nutrition, 9(8) (8), 4232 - 4242, English, International magazine[Refereed]Scientific journal
- Nov. 2019, BIOORGANIC & MEDICINAL CHEMISTRY, 27(22) (22), 115120 - 115120, English, International magazine[Refereed]Scientific journal
- Feb. 2019, BIOCHEMICAL SOCIETY TRANSACTIONS, 47(1) (1), 179 - 185, English, International magazine[Refereed]
- Elsevier, Jan. 2019, Comprehensive Biotechnology, 169 - 180, EnglishIn book
- Jan. 2019, MICROBIAL BIOTECHNOLOGY, 12(1) (1), 77 - 97, English[Refereed]Scientific journal
- Jan. 2017, NATURE COMMUNICATIONS, 8, 14007 - 14007, English, International magazine[Refereed]Scientific journal
- Jan. 2015, BREEDING SCIENCE, 65(1) (1), 77 - 84, English, Domestic magazine[Refereed]Scientific journal
- May 2014, BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY, 77(5) (5), 1104 - 1107, English, International magazine[Refereed]Scientific journal
- Jan. 2014, PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 111(1) (1), E54 - E61, English, International magazine[Refereed]Scientific journal
- Dec. 2013, PLOS ONE, 8(7) (7), e67385, English, International magazine[Refereed]Scientific journal
- Feb. 2013, BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS, 431(2) (2), 176 - 180, English, International magazine[Refereed]Scientific journal
- 2012, Environmental Control in Biology, 50(3) (3), 237 - 246, English[Refereed]Scientific journal
- Elsevier Inc., Sep. 2011, Comprehensive Biotechnology, Second Edition, 4, 165 - 176, English[Refereed]In book
- Jul. 2011, PLANT MOLECULAR BIOLOGY, 76(3-5) (3-5), 335 - 344, English, International magazine[Refereed]Scientific journal
- Nov. 2010, GM Crops, 1, 322 - 326, EnglishGeneration of transplastomic lettuce with enhanced growth and high yield.[Refereed]Scientific journal
- Sep. 2010, PLANT JOURNAL, 63(5) (5), 766 - 777, English, International magazine[Refereed]Scientific journal
- Feb. 2010, BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS, 392(2) (2), 212 - 216, English, International magazine[Refereed]Scientific journal
- Sep. 2009, ACTA CRYSTALLOGRAPHICA SECTION D-STRUCTURAL BIOLOGY, 65, 942 - 951, English[Refereed]Scientific journal
- Sep. 2009, PLANT PHYSIOLOGY, 151(1) (1), 114 - 128, English, International magazine[Refereed]Scientific journal
- 2,3-Diketo-5-methylthiopentyl-1-phosphate enolase (DK-MTP-1P enolase), a RuBisCO-like protein (RLP), catalyzes the enolization of 2,3-diketo-5-methylthiopentyl-1-phosphate. The crystal structure of the apo decarbamylated form (E form) of Bacillus subtilis DK-MTP-1P enolase (Bs-DK-MTP-1P enolase) has been determined at 2.3 A resolution. The overall structure of the E form of Bs-DK-MTP-1P enolase highly resembles that of Geobacillus kaustophilus DK-MTP-1P enolase (Gk-DK-MTP-1P enolase), with the exception of a few insertions or deletions and of a few residues at the active site. In the E form of Bs-DK-MTP-1P enolase, Lys150 (equivalent to Lys175 in RuBisCO) at the active site adopts a conformation that is distinct from those observed in the other forms of Gk-DK-MTP-1P enolase. This unusual conformational change appears to be induced by changes in the varphi and psi angles of Gly151, which is conserved in the sequences of the Bs-DK-MTP-1P and Gk-DK-MTP-1P enolases but not in those of RuBisCOs. The loop at 303-312, equivalent to the catalytic loop termed ;loop-6' in RuBisCO, is in a closed conformation in the E form of Bs-DK-MTP-1P enolase. The closed conformation appears to be stabilized by Pro312, which is conserved in the sequences of several RLPs (equivalent to Glu338 in RuBisCO). Based on these results, the characteristic structural features of DK-MTP-1P enolase are discussed.Sep. 2009, Acta crystallographica. Section D, Biological crystallography, 65(Pt 9) (Pt 9), 942 - 51, English, International magazine[Refereed]Scientific journal
- May 2009, JOURNAL OF BIOLOGICAL CHEMISTRY, 284(19) (19), 13256 - 13264, English, International magazine[Refereed]Scientific journal
- Feb. 2009, ACTA CRYSTALLOGRAPHICA SECTION F-STRUCTURAL BIOLOGY COMMUNICATIONS, 65(Pt 2) (Pt 2), 147 - 150, English, International magazine[Refereed]Scientific journal
- May 2008, JOURNAL OF EXPERIMENTAL BOTANY, 59(7) (7), 1543 - 1554, English, International magazine[Refereed]Scientific journal
- Apr. 2008, BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY, 72(4) (4), 959 - 967, English[Refereed]Scientific journal
- 2008, ACTA CRYSTALLOGRAPHICA A-FOUNDATION AND ADVANCES, 64, C261 - C262, English[Refereed]
- Jan. 2008, PROTEIN SCIENCE, 17(1) (1), 126 - 135, English[Refereed]Scientific journal
- 2008, PLANT BIOTECHNOLOGY, 25(3) (3), 285 - 290, English[Refereed]Scientific journal
- Aug. 2007, BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY, 71(8) (8), 2021 - 2028, English[Refereed]Scientific journal
- 2007, PLANT AND CELL PHYSIOLOGY, 48, S71 - S71, EnglishImprovement of cyanobacterial RuBisCO by introducing the latch structure of red algal RuBisCO with high specificity for CO2 fixation.[Refereed]
- 2007, PLANT AND CELL PHYSIOLOGY, 48, S214 - S214, EnglishCharacterization of Arabidopsis mutants for quantitative regulation of RuBisCO.[Refereed]
- Aug. 2006, JOURNAL OF BIOLOGICAL CHEMISTRY, 281(34) (34), 24462 - 24471, English[Refereed]Scientific journal
- Ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBisCO) is a key enzyme in photosynthetic CO2 fixation. In higher plants, RuBisCO is a multimeric enzyme composed of large and small subunits encoded by the chloroplast rbcL gene and nuclear rbcS genes. RuBisCO is biosynthesized via complex processes, hence overall mechanism is still unknown. To understand the molecular mechanism for these processes, we have designed a positive method for screening RuBisCO biosynthesis mutants using methionine sulfoximine (MSX) which is an inhibitor of glutamine synthetase. Wild-type plants treated with MSX could not survive because photorespiratory NH3 accumulated massively depending on RuBisCO oxygenase activity. In contrast, rca mutants which lacked the activation of RuBisCO could survive under the same condition. After screened of 11000 EMS mutagenized seedlings, we obtained eight mutants which show either decreased RuBisCO amounts or low activities. These results indicate that this system is useful for screening of RuBisCO biosynthesis mutants.The Japanese Society of Plant Physiologists, 2006, Plant and Cell Physiology Supplement, 2006, 119 - 119
- Jun. 2005, RESEARCH IN MICROBIOLOGY, 156(5-6) (5-6), 611 - 618, English[Refereed]Scientific journal
- Jun. 2005, ACTA CRYSTALLOGRAPHICA SECTION F-STRUCTURAL BIOLOGY AND CRYSTALLIZATION COMMUNICATIONS, 61, 595 - 598, English[Refereed]Scientific journal
- 2005, ACTA CRYSTALLOGRAPHICA A-FOUNDATION AND ADVANCES, 61, C207 - C208, English[Refereed]
- Mar. 2004, BMC MICROBIOLOGY, 4, English[Refereed]Scientific journal
- Oct. 2003, SCIENCE, 302(5643) (5643), 286 - 290, English[Refereed]Scientific journal
- Feb. 2002, JOURNAL OF MOLECULAR BIOLOGY, 316(3) (3), 679 - 691, English[Refereed]Scientific journal
- (株)インフォノーツパブリッシング, Dec. 2019, 機能性食品と薬理栄養, 13(3) (3), 180 - 180, Japanese低分子抗酸化物含有食による糖尿病モデルマウス血糖コントロールの改善Summary national conference
- 01 Nov. 2018, Journal of the Society of Inorganic Materials, Japan, 25(397) (397), 406‐411, Japanese二酸化炭素の環境問題と利用 光合成二酸化炭素固定酵素RuBisCO
- Oct. 2017, 酵素工学ニュ-ス, (78) (78), 14‐18, Japaneseメタン生成アーキアにおけるRuBisCOを利用した新規CO2固定経路
- 日本農芸化学会 ; 1962-, 20 Jan. 2017, 化学と生物, 55(2) (2), 88‐97 - 97, Japanese
- 日本化学会, 01 Nov. 2016, 化学と工業, 69(11) (11), 957‐959 - 959, JapaneseCO2資源化:研究者たちの挑戦 4 CO2資源化を目指した光合成炭素固定酵素RuBisCOの機能進化研究
- (公社)日本生化学会, Dec. 2015, 日本生化学会大会・日本分子生物学会年会合同大会講演要旨集, 88回・38回, [1P0546] - [1P0546], Englishヒトチオレドキシン-1高発現レタス長期食餌負荷による糖尿病モデルマウス血糖コントロールの改善
- 05 Mar. 2014, 日本農芸化学会大会講演要旨集(Web), 2014, 2C04A08 (WEB ONLY), Japaneseジャガイモ塊茎を形成するストロンの原基である地中腋芽におけるRanGTPase1遺伝子の発現解析
- 日本生物工学会, 25 Jun. 2013, 生物工学会誌, 91(6) (6), 352 - 352, Japaneseシアノバクテリアの光合成能力を利用したバイオ燃料生産
- Jun. 2013, 生物工学会誌, 91(6) (6), 352, Japaneseシアノバクテリアの光合成能力を利用したバイオ燃料生産[Invited]Introduction scientific journal
- The production of human therapeutic proteins in plants provides opportunities for low-cost production, and minimizes the risk of contamination from potential human pathogens. Chloroplast genetic engineering is a particularly promising strategy, because plant chloroplasts can produce large amounts of foreign target proteins. Human thioredoxin 1 (hTrx1) is an antioxidant protein, and can suppress various diseases in mice. Therefore, hTrx1 is a prospective candidate as a human therapeutic protein.The Japanese Society of Plant Physiologists, 11 Mar. 2011, 日本植物生理学会年会要旨集, 52nd, 129 - 75, Japanese
We created transplastomic lettuce expressing hTrx1 gene under the control of the tobacco psbA promoter. The hTrx1 protein accumulated to approximately 3% of total soluble protein in mature leaves. The hTrx1 protein purified from lettuce leaves was functionally active, and reduced insulin disulfides. The purified protein protected MIN6 cells from damage by hydrogen peroxide, as reported previously for a recombinant hTrx1 form Escherichia coli. This is the first report for expression of the biologically active hTrx1 protein in plant chloroplasts. Considering that this expression host is an edible crop plant, this transplastomic lettuce may be suitable for oral delivery of hTrx1. - Japan Society for Bioscience, Biotechnology, and Agrochemistry, 01 Nov. 2010, 化学と生物, 48(11) (11), 739 - 742, Japanese
- 29 Sep. 2010, バイオテクノロジーシンポジウム予稿集, 28th, 56 - 57, Japanese医・農・工融合によるヒトチオレドキシン1産生レタスの生産技術の開発
- 酵素工学研究会, 25 Apr. 2008, 酵素工学研究会講演会講演要旨集, 59, 11 - 18, Japanese光合成CO2固定酵素RuBisCOとRuBisCO-like Proteinの比較研究が明らかにしたこと--RuBisCOはどのようにCO2固定能を獲得したのか? (酵素工学研究会第59回講演会)
- Dec. 2007, 光合成研究, 17, 84 - 86Rubisco satellite meeting Reaserch Frontiers with Rubisco, the “Elixir of Life” in the Biospherに参加して[Invited]
- 06 Nov. 2007, バイオテクノロジーシンポジウム予稿集, 25th, 117 - 118, Japanese医・農・工融合によるヒトチオレドキシン1産生レタスの生産技術の開発
- Feb. 2007, PHOTOSYNTHESIS RESEARCH, 91(2-3) (2-3), 232 - 232, EnglishImprovement of cyanobacterial RuBisCO by introducing the latch structure involved in high affinity for CO2 in red algal RuBisCO.Summary international conference
- Feb. 2007, PHOTOSYNTHESIS RESEARCH, 91(2-3) (2-3), 231 - 232, EnglishEvolutionary potential of RuBisCO-like protein in Bacillus subtilis: Interaction with transition-state analogue of RuBisCO.Summary international conference
- Feb. 2007, PHOTOSYNTHESIS RESEARCH, 91(2-3) (2-3), 264 - 264, EnglishIsolation and characterization of genes necessary for achievement of RuBisCO accumulation in Arabidopsis thaliana.Summary international conference
- 01 Dec. 2006, Journal of plant research, 119, 13 - 13, EnglishThe completion of the Calvin cycle via molecular evolution
- 2006, 日本植物生理学会年会要旨集, 47thRuBisCO生合成機構の分子遺伝学的解析
- 2005, PLANT AND CELL PHYSIOLOGY, 46, S75 - S75, EnglishStructure-function relationship between photosynthetic RuBisCO and the RuBisCO-like protein of Bacillus subtilisSummary international conference
- 日本農芸化学会, Jul. 2004, 化学と生物, 42(7) (7), 424 - 426, Japanese光合成CO2固定酵素RuBisCOの起源が明らかに! 枯草菌のメチオニン代謝酵素RLPに秘められた進化の跡[Refereed][Invited]
- 2003, PLANT AND CELL PHYSIOLOGY, 44, S61 - S61, EnglishThe common reaction between photosynthetic Ribulosebisphosphate carboxylase/oxygenase (RuBisCO) and Bacillus subtilis RuBisCO-like protein (RLP)Summary international conference
■ Lectures, oral presentations, etc.
- 日本共生生物学会第7回大会, Japaneseラパザの核ゲノムコード「盗」葉緑体タンパク質Oral presentation
- 環境変動の生態・生理学に関する研究会, 2016, Japanese, Domestic conference植物を用いた未来型医薬用タンパク質生産Public discourse
- 日本化学会第96回春季年会特別企画 生命化学研究から見たCO2資源化:光合成研究と人工光合成の融合を目指して, 2016, Japanese, Domestic conference光合成CO2固定酵素RuBisCOの機能進化研究からのCO2資源化への展開[Invited]Invited oral presentation
- 日本農芸化学会2016年度大会, 2016, Japanese, Domestic conferenceC4光合成の炭酸固定酵素と脱炭酸酵素のC3植物への導入による代謝系の改変:水ストレス耐性の向上とその基盤のメタボローム解析Poster presentation
- 環境変動の生態・生理学に関する研究会, Mar. 2015, Japanese, Domestic conference光合成炭素固定酵素の機能進化Oral presentation
- 日本農芸化学会 農芸化学奨励賞受賞講演会, Mar. 2015, Japanese, Domestic conference光合成CO2固定酵素RuBisCOの機能進化研究[Invited]Invited oral presentation
- 日本農芸化学会関西支部第492回講演会 2015年度日本農芸化学会奨励賞受賞講演, 2015, Japanese, Domestic conference光合成CO2固定酵素RuBisCOの機能進化研究[Invited]Invited oral presentation
- 第38回 日本分子生物学会, 2015, Japanese, Domestic conferenceヒトチオレドキシン-1高発現レタス長期食餌負荷による糖尿病モデルマウス血糖コントロールの改善Poster presentation
- 日本植物生理学会2014年度大会, Mar. 2014, Japanese, Domestic conference‘C4化’タバコにおける水利用効率および乾燥ストレス耐性の向上:δ13Cの測定およびメタボローム解析とアミノ酸分析による性格付けOral presentation
- 日本農芸化学会2014年度大会, Mar. 2014, Japanese, Domestic conferenceジャガイモ塊茎を形成するストロンの原基である地中腋芽におけるRanGTPase1遺伝子の発現機構Oral presentation
- 日本農芸化学会2014年度大会, Mar. 2014, Japanese, Domestic conferenceシアノバクテリアにおけるRuBisCO発現量によるカルボキシソーム形成制御機構Oral presentation
- 日本農芸化学会2014年度大会, Mar. 2014, Japanese, Domestic conferenceアーキア型phosphoribulokinaseの機能解析Oral presentation
- 日本化学会第94回春季年会, Mar. 2014, English, 名古屋大学, Domestic conferenceApplications of sequence-specific DNA binding adaptors for assembling proteins on DNA origamiOral presentation
- JSTさきがけ第6回領域会議, Feb. 2014, Japanese, Domestic conferenceバイオ燃料高生産のための炭素固定能を強化したスーパーシアノバクテリアの創成Others
- 第27回インターゲノミクスセミナー, Dec. 2013, Japanese, Domestic conference光合成CO2固定酵素ルビスコの機能進化を探るPublic discourse
- JSTさきがけ研究報告会, Nov. 2013, Japanese, Domestic conferenceバイオ燃料高生産のための炭素固定能を強化したスーパーシアノバクテリアの創成Public discourse
- 第4回藻類バイオ燃料生産技術研究会, Sep. 2013, Japanese, Domestic conferenceラン藻を用いたエタノール高生産を目指したルビスコ機能強化研究Public discourse
- 東京大学生産技術研究所 第1回応用化学セミナー, Jul. 2013, Japanese, Domestic conference光合成CO2固定酵素ルビスコの基礎研究とその成果を用いた応用研究Public discourse
- 日本Archaea研究会第26回講演会, Jul. 2013, Japanese, Domestic conferenceアーキアが有する光合成カルビンサイクル酵素phosphoribulokinaseホモログの酵素学的解析Oral presentation
- 30th of the Gordon conference of Archaea, Jul. 2013, English, Italy, International conferenceEnzymatic analysis of archaeal homologues of phosphoribulokinase, a key enzyme in the photosynthetic Calvin cycle.Poster presentation
- 第4回日本光合成学会年会, Jun. 2013, Japanese, Domestic conferenceC4光合成の炭素固定酵素(PEPC)と脱炭酸酵素(PCK)を葉緑体内で過剰発現させたタバコ(C3植物)における光合成能、水利用効率(WUE)および浸透圧ストレス耐性Oral presentation
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (B), Fukui University of Technology, 01 Apr. 2024 - 31 Mar. 2027Biochemical demonstration and functional verification of chimeric complex formation in kleptoplasy
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Challenging Research (Exploratory), Challenging Research (Exploratory), Kobe University, 28 Jun. 2019 - 31 Mar. 2022Analysis of the molecular evolution of photosynthetic CO2-fixing pathwayThe Calvin cycle is a primary metabolic pathway for CO2-fixing in plants, algae, and cyanobacteria. Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) is the CO2-fixing enzyme in the Calvin cycle. Methanogenic archaea are not photosynthetic organisms but possess a unique CO2-fixing cycle which is composed of partial steps including RuBisCO catalyzing step from the Calvin cycle and Ribulose monophosphate pathway. Therefore, the methanogenic archaeal CO2-fixing pathway is thought to be a primitive metabolism of the photosynthetic Calvin cycle. In order to study molecular evolution of the Calvin cycle, we analyzed enzymatic properties of RuBisCO in this CO2-fixing pathway. Methanogenic archaeal RuBisCO shows very low maximum reaction rate for the carboxylase reaction and CO2/O2 relative specificity factor, as compared with photosynthetic RubisCOs.
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B), Grant-in-Aid for Scientific Research (B), Kobe University, 01 Apr. 2017 - 31 Mar. 2021, Principal investigatorWe found that the small subunit of Ribulose 1,5-bisphospate carboxylase/oxygenase (RuBisCO) is involved in the determination of CO2/O2 relative specificity in cyanobacterial RuBisCOs. Enzymatic analysis of metanogenic archaeal RuBisCO revealed that this enzyme showed the most lowest CO2/O2 relative specificity among RuBisCOs. We identified RuBisCO activase which catalyzes the activation of this enzyme in cyanobacteria.Competitive research funding
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B), Grant-in-Aid for Scientific Research (B), Kobe University, 01 Apr. 2014 - 31 Mar. 2017, Principal investigatorWe found methanogenic archaeal RuBisCO functions in the novel CO2 fixation pathway which has some different steps from the photosynthetic Calvin cycle, suggesting that this novel pathway should be the ancient Calvin cycle. Enzymatic analysis of hybrid RuBisCO created by swap of large and small subunits between thermophilic cyanobacteria RuBisCO with high CO2 specificity and mesophilic cyanobacteria RuBisCO revealed that small subunit was involved in CO2 specificity. Transplastomic tobacco with over expression of RuBisCO activase tends to be enhanced a photosynthetic CO2 fixation rate.Competitive research funding
- 戦略的創造研究推進事業 個人型研究さきがけ, 2013, Principal investigatorさきがけ「バイオ燃料高生産のための炭素固定能を強化したスーパーシアノバクテリアの創成」Competitive research funding
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B), Grant-in-Aid for Scientific Research (B), Nara Institute of Science and Technology, 2009 - 2011Molecular basis of productivity improvement through sink development of potatoThis study was done to clarify the mechanism of promotion of photosynthesis in the source organ and accumulation of starch in the sink organ in potato plants. The gene was a member of the RanGTPase family. We established the in vitro stolon induction system using potato expalnts with axillary buds to analyze the expression of two RanGTPase genes. The results showed clearly that one of the two endogenous genes was exclusively induced in the initial phase of the stolon induction.
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (A), Grant-in-Aid for Young Scientists (A), Nara Institute of Science and Technology, 2009 - 2011Enhancement of plant photosynthesis by functional improvement of CO_2-fixing enzyme RuBisCO.Residues for functional improvement of RuBisCO were identified by the results form studies of thermophilic cyanobacterial RuBisCO and RuBisCO ancestral protein from Bacillus. I found a pre-Calvin cycle for CO_2 fixation using RuBisCO in methanogenic archaeon. Improvement of plant RuBisCO by replacement with red-algal residue enabled to perform a normal photosynthetic CO_2-fixing with low RuBisCO level in tobacco. The genes necessary for the achievement of RuBisCO accumulation were identified for quantitative enhancement of RuBisCO to increase photosynthetic capacity.
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (A), Grant-in-Aid for Young Scientists (A), Nara Institute of Science and Technology, 2006 - 2008Improvement of CO2-fixing enzyme, RuBisCO, based on molecular evolution to enhance photosynthesis of plant.ルビスコ祖先タンパク質とルビスコの比較解析から、両酵素で共通な触媒残基を明らかにした。これを基に祖先タンパク質にルビスコ触媒必須残基を導入し、試験管内でルビスコへの分子進化に成功した。紅藻ルビスコが持つ高CO_2識別残基をラン藻ルビスコに導入し、CO_2識別能を20%高めることに成功した。さらに、この残基をタバコルビスコに導入したタバコ形質転換体を作出した。紅藻ルビスコ遺伝子導入タバコの解析から、高機能外来性ルビスコの葉緑体機能発現の問題点を明らかにし、その解決策を導き出した。
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A), Grant-in-Aid for Scientific Research (A), Nara Institute of Science and Technology, 2005 - 2008Molecular mechanism of functions of photosynthetic CO_2-fixing enzyme RuBisCOルビスコの反応触媒の分子機構およびルビスコ生合成の制御機構の解明を行ってきた.ルビスコ反応触媒の分子機構の解明を目指し、すでに枯草菌に発見しているルビスコ活性を持たないルビスコ祖先蛋白質とルビスコの反応中心残基の触媒反応への関わり方を明らかにした.我々が発見したもっとも高いSrel値を持つ紅藻Galdieriaルビスコと植物ルビスコの蛋白質構造比較から、オキシゲナーゼ反応抑制残基と想定している残基をラン藻ルビスコへ導入し、その機能を明らかにした.ルビスコ生合成の制御機構に関しては、ルビスコを正常に合成できない変異株を多数スクリーニングし、分子遺伝学手法によってそれらの変異原因遺伝子を特定し、その機能解析からルビスコ生合成の制御機構を明らかにした.
- 補助金, 2005分子進化に基づいたRuBisCOの改良光合成カルビンサイクルにおいてCO2固定反応を触媒しているのが、ribulose bisphosphate carbaxylase/oxygenase (RuBisCO)である。RuBisCOはCO2とだけでなくO2との反応(オキシゲナーゼ反応)を示し、オキシゲナーゼ反応はカルボキシラーゼ反応を拮抗的に阻害する。また、RuBisCOの反応速度は一般の酵素と比較し、非常に遅く、その速度は1秒間に2〜3回である。これらの理由から、植物光合成はRuBisCOによって律速されている。このような現状から、O2との反応性を抑制し、反応速度を高めたRuBisCOを創成し、植物内で機能させることによる光合成CO2固定の促進が期待されている。私の研究テーマは、理想型のRuBisCOへの機能改良である。Competitive research funding
- ライフサイエンス基礎科学研究, 2005植物光合成改良・光合成CO2固定酵素改良光合成CO2固定酵素の改良を行い、植物光合成効率の向上を目指すCompetitive research funding