1998 Fiscal Year Final Research Report Summary
New chloroplast genes involved in assembly of photosystem 1 complex.
| Project/Area Number |
09640774
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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 | Okayama University |
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Principal Investigator |
TAKAHASHI Yuichiro Okayama University, Department of Biology, Associate Professor, 理学部, 助教授 (50183447)
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| Project Period (FY) |
1997 – 1998
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| Keywords | photosynthesis / photosystem 1 / ycf3 / ycf4 / molecular assembly / Chlamydomonas reinhardtii / chloroplast transformation / molecular chaperone |
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| Research Abstract |
The photosystem 1 drives light-induced electron transfer reaction from plastocyanin to ferredoxin and consists of more than ten subunits and over one hundred cofactors. The biogenesis of this complex requires cooperative assembly of these components.
In the present study, the chloroplast genes ycf3 and ycf4 from the green alga Chiamydomonas reinhardtii have been characterized. Using biolistic transformation, ycf4 or were disrupted with a chioroplast selectable marker cassette. Transformants lacking ycf4 or ycf3 were unable to grow photoautotrophically and were deficient in photosystem I activity. Western blot analysis showed that the photosystem I (PSI) complex does not accumulate stably in thylakoid membranes of these transformants. Ycf4 and Ycf3 were localized on thylakoid membranes but not stably associated with the PSI complex and accumulated to wild type levels in mutants lacking PSI.RNA blot hybridizations showed that transcripts of psaA, psaB and psaC accumulate normally in these mutants and use of chimeric reporter genes revealed that Ycf3 is not required for initiation of translation of psaA and psaB mRNA.Our results indicate that Ycf3 and Ycf4 are required for stable accumulation of the PSI complex.
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