| Budget Amount *help |
¥4,680,000 (Direct Cost: ¥3,600,000、Indirect Cost: ¥1,080,000)
Fiscal Year 2014: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2013: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2012: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2011: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
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| Outline of Final Research Achievements |
The a subunit of the Na+-transporting FoF1 ATP synthase plays a key role in Na+ transport. It forms half channels that allow Na+ to enter and leave the carboxyl group on c subunits. The essential R226, which faces the carboxyl group of c subunits in the middle of transmembrane helix of the a subunit, separates the cytoplasmic and periplasmic half-channels. To elucidate contributions of other amino acid residues of the transmembrane helix using hybrid FoF1 (Fo from Propionigenium modestum and F1 from thermophilic Bacillus PS3), 25 residues were individually mutated to Cys, and effects of modification with the SH-modifying agent N-ethylmaleimide (NEM) on ATP synthesis and hydrolysis activity were analyzed. NEM inhibited ATP synthesis and hydrolysis activities of A214C, G215C, A218C, I223C and N230C mutants and inhibited ATP synthesis activity of the K219C mutant. Thus, these residues contribute to the integrity of the Na+ half channel, and both half channels are present in the a subunit.
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