| Project/Area Number |
09640767
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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 | Nagoya University |
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Principal Investigator |
OGAWA Teruo Nagoya University Bioscience Center, Professor, 生物分子応答研究センター, 教授 (80087593)
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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 |
¥3,000,000 (Direct Cost: ¥3,000,000)
Fiscal Year 1998: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1997: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Keywords | cyanobacteria / proton extrusion / Synechocystis / Synechococcus / pxcA / cotA / cytoplasmic membrane / cemA / らん藻 / プロトン輸送 / cotA-pxcA / 変異株 / CO_2取り込み / NO_3^-取り込み |
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| Research Abstract |
Light-induced proton extrusion has been observed with various strains of cyanobacteria. We found that pxcA (formerly named as cotA) complemented a Synechocystis mutant unable to grow at acidic pH and that inactivation of this gene abolished the activity of light-induced proton extrusion. PxcA genes of Synechocystis PCC6803 and Synechococcus PCC7942 encode proteins of 440 and 427 amino acids, respectively, that showed significant sequence homology to a protein in the inner envelope membrane of chloroplasts encoded by cemA in chloroplast genome. We have demonstrated that PxcA is localized in the cytoplasmic membrane. The pxcA-inactivated mutant was unable to grow at acidic pHs or at low Na^+ concentrations. The activities of CO_2 uptake and NO_3 uptake by the mutant were inhibited under these conditions. There are two types of CemA/PxcA.CemA in chloroplasts of higher plants consists of 229 - 231 amino acids whereas CemA/PxcA in liverwort, Chlamydomonas and cyanobacteria are much larger and consist of 421-500 amino acids. Both short and long types of CemA/PxcA contain 4 membrane spanning domains. Phylogenetic tree for PxcA of cyanobacteria and CemA of plants and Chlamydomonas suggested that PxcA and CemA have the same ancestor.
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