Analysis of ion transporting mechanism of sodium transporting ATP synthase

2015 Fiscal Year Final Research Report

• Project/Area Number: 23770160
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Functional biochemistry
• Research Institution: Ube National College of Technology
• Principal Investigator: Mitome Noriyo 宇部工業高等専門学校, 物質工学科, 准教授 (90431981)
• Project Period (FY): 2011-04-28 – 2016-03-31
• Keywords: イオンチャネル / ATP合成酵素 / イオン輸送

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.

Free Research Field

生物化学