| Project/Area Number |
09308021
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| Research Category |
Grant-in-Aid for Scientific Research (A).
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Structural biochemistry
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| Research Institution | University of Tokyo |
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Principal Investigator |
TOKUDA Hajime Institute of Molecular and Cellular Biosciences, University of Tokyo Professor, 分子細胞生物学研究所, 教授 (40125943)
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| Co-Investigator(Kenkyū-buntansha) |
NISHIYAMA Ken-ichi Institute of Molecular and Cellular Biosciences, University of Tokyo Assistant professor, 分子細胞生物学研究所, 助手 (80291334)
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| Project Period (FY) |
1997 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥13,900,000 (Direct Cost: ¥13,900,000)
Fiscal Year 2000: ¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 1999: ¥5,000,000 (Direct Cost: ¥5,000,000)
Fiscal Year 1998: ¥5,800,000 (Direct Cost: ¥5,800,000)
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| Keywords | proton motive force / ATP / secretory protein / membrane translocation / lipoprotein / outer membrane localization / 蛋白質の膜透過 / 蛋白質の膜局在化 / ABCトランスポーター / Sec因子 / 膜局在化 / 相互作用 / 蛋白質分泌 / 膜小胞 / SecA / リポタンパク質 / LolA |
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| Research Abstract |
Protein translocation across the E.coli cytoplasmic membrane is catalyzed by a Sec macinery comprising six Sec factors. Among them, SecA undergoes the membrane-insertion and -deinsertion cycle upon the binding and hydrolysis of ATP, respectively. The SecA cycle is the direct driving force for protein translocation. SecG, a membrane component of the machinery, also undergoes a membrane topology inversion cycle, which is coupled to the SecA cycle. In this research project, we revealed that the SecG cycle facillitates the SecA cycle, thereby causing efficient protein translocation. Moreover, a protein motive force was also found to accerelate the SecA cycle.
Maturation of lipoproteins takes place on the outer surface of the cytoplasmic membrane. Lipoproteins having other than Asp residue at the +2 position are released from the cytoplasmic membrane and localized to the outher membrane. We previously found that LolA, a lipoprotein-specific molecular chaperone in the periplasm, forms a complex with outer membrane-directed lipoprotein, but not inner membrane-specific one having Asp at +2 position. In this research project, we found that LolB and LolCDE complex are also essential for the sorting and membrane-specific localization of lipoproteins. LolB is an outer membrane receptor for lipoprotein. The LolCDE complex belongs to the ABC transport super family and mediates the release of lipoprotein from the cytoplasmic membrane.
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