期刊
FEBS LETTERS
卷 555, 期 1, 页码 29-34出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/S0014-5793(03)01101-3
关键词
ATP synthase; proton transport; rotary motor; aqueous access channel; cysteine chemical modification; subunit a; subunit c
资金
- NIGMS NIH HHS [GM23105] Funding Source: Medline
F1F0 ATP synthases generate ATP by a rotary catalytic mechanism in which H+ transport is coupled to rotation of an oligomeric ring of c subunits extending through the membrane. Protons bind to and then are released from the aspartyl-61 residue of subunit c at the center of the membrane. Subunit a of the F-0 sector is thought to provide proton access channels to and from aspartyl-61. Here, we summarize new information on the structural organization of Escherichia coli subunit a and the mapping of aqueous-accessible residues in the second, fourth and fifth transmembrane helices (TMHs). Aqueous-accessible regions of these helices extend to both the cytoplasmic and periplasmic surface. We propose that aTNM4 rotates to alternately expose the periplasmic or cytoplasmic half-channels to aspartyl-61 of subunit c during the proton transport cycle. The concerted rotation of interacting helices in subunit a and subunit c is proposed to be the mechanical force driving rotation of the c-rotor, using a mechanism akin to meshed gears. (C) 2003 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.
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