| Project/Area Number |
18570126
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Functional biochemistry
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| Research Institution | Kyoto University |
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Principal Investigator |
KODAKI Tsutomu Kyoto University, Institute of Advanced Energy, Bioenerv Researth Safiun, Associate Professor (70170264)
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| Co-Investigator(Kenkyū-buntansha) |
MAKINO Keisuke KYOTO UNIVERSITY, Institute of Advanced Energy, Bioenerv Researth Safiun, Professor (50159141)
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| Project Period (FY) |
2006 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥4,010,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥510,000)
Fiscal Year 2007: ¥2,210,000 (Direct Cost: ¥1,700,000、Indirect Cost: ¥510,000)
Fiscal Year 2006: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Keywords | Carbohydrate Metabolism / Biomass / Arabinose / Enzyme / Efficient Conversion |
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| Research Abstract |
L-Arabinose is a major constituent of some plant materials, and L-arabinose catabolism is therefore relevant for microorganisms using plant material as a carbon source. The metabolic pathway from L-arabinose to D-xylulose 5-phosphate in bacterium has been investigated extensively. It is believed that there are two alternative pathways for bacterial L-arabinose metabolism, which do not involve a phosphorylation reaction, in contrast to the known bacterial pathway. In the first pathway, L-arabinose is oxidized to L-arabino-γ-lactone by NAD(P)+-dependent dehydrogenase. The lactone is cleaved by a lactonase to L-arabonate, followed by two successive dehydration reactions forming L-2-keto-3-deoxyarabonate (L-KDA) and α-ketoglutaric semialdehyde. The last step is the NAD(P)+-dependent dehydrogenation of the semialdehyde to α-ketoglutaric acid. The second pathway has the same initial three steps, but L-KDA is cleaved through an aldolase reaction to glycoaldehyde and pyruvate. No gene-encoding enzyme involved in these alternative pathways of L-arabinose metabolism had been identified so far. In this study, L-arabinose 1-dehydrogenase catalyzing the conversion of L-arabinose to L-arabino-γ-lactone was characterized as an enzyme responsible for the first step of this alternative pathway of L-arabinose metabolism. The gene encoding L-arabinose 1-dehydrogenase was cloned using a partial peptide sequence of the purified enzyme and was overexpressed in Escherichia coli as a fully active enzyme. This is the first identification of a gene involved in an alternative pathway of L-arabinose metabolism in bacterium. Furthermore, the four other enzymes and the relevant genes were also characterized as L-arabinonolactonase, L-arabonate dehydratase, L-2-keto-3-deoxyarabonate dehydratase, and α-ketogoutaric semialdehyde dehydrogease by biochemical analysis.
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