| Project/Area Number |
09640771
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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 |
植物生理
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| Research Institution | Osaka University |
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Principal Investigator |
SAEKI Kazuhiko Osaka University, Department of Biology, Graduate School of Science, Lecturer, 大学院・理学研究科, 講師 (40201511)
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| Project Period (FY) |
1997 – 1998
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| Project Status |
Completed (Fiscal Year 1998)
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| Budget Amount *help |
¥2,700,000 (Direct Cost: ¥2,700,000)
Fiscal Year 1998: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1997: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Keywords | RHODOBACTER / FERREDOXIN / ELECTRON-TRANSPORT / NITROGEN-FIXATION / NADH / MEMBANE-PROTEIN-COMPLEX / 光合成細菌 / rnf遺伝子 |
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| Research Abstract |
The rnf(rbodobacter nitrogen fixation)operon in Rhodobacter capsutatus is essential for nitrogen fixation under light. We showed that products of the rnf operon constitute a protein complex in chromatophore membrane and proposed that the complex has a chimerie construct of two subcomplexes, one transmembrane subcomplex similar to Na^+-translocating NADH quinone oxidoreductase and the other peripheral subcomptex similar to H^+-translocating NADH quinone oxidoreductase. Its function should : be energy-consuming NADH-ferredoxin oxidoreductase. 1) We revealed that the complex is also required for nitrogen fixation under dark anaerobic conditions using dimethylsulfoxide as a terminal electron acceptor this agrees that the Rnf complex functions without direct link to photosynthetic reaction center. 2) Presence of at least one Fe-S center in Rnf complex was identified by EPR analysis The cluster showed a novel signal, g=1 .84, at 10K with extremely low redox potential. Since other strong signals from succinate-quinone oxidoreductase interfered detailed analysis, we are currently seeking conditions and mutants to overcome this difficulty. 3) Escheriehia coil and four other non-diazotrophic bacteria possess homologous of the rnf operon. Over expression of the E.coil homologue in E.ccli seemed lethal. This E.coli operon did not complemented the rnf-null mutants of R.capsulatus. 4) Chemical crosslinking studies showed that RnfC subunit of the complex interacts closely with a 20K Dalton peptide, which is possibly RnfB or RnfA peptide.
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