Mechanics of coupling proton movements to c‐ring rotation in ATP synthase

FEBS Letters

Dmitriev, Oleg Y¹  Angevine, Christine M¹  Fillingame, Robert H¹ 

[1] Department of Biomolecular Chemistry, 1300 University Avenue, University of Wisconsin Medical School, Madison, WI 53706, USA

关键词: ATP synthase;    Proton transport;    Rotary motor;    Aqueous access channel;    Cysteine chemical modification;    Subunit a;    Subunit c;    NEM;    N-ethyl-maleimide;    TMH;    transmembrane helix;   

DOI  :  10.1016/S0014-5793(03)01101-3

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

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 F₀ 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 aTMH4 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.

【 授权许可】

Unknown