Coupling proton movements to c-ring rotation in F1F0 ATP synthase:: aqueous access channels and helix rotations at the a-c interface
Coupling proton movements to c-ring rotation in F1F0 ATP synthase:: aqueous access channels and helix rotations at the a-c interface
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DOI：
10.1016/s0005-2728(02)00250-5
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发表时间：
2002-09-10
影响因子：
4.3
通讯作者：
Dmitriev, OY
中科院分区：
文献类型：
--
作者：
Fillingame, RH;Angevine, CM;Dmitriev, OY
F1F0 ATP synthases generate ATP by a rotary catalytic mechanism in which H+ transport is coupled to rotation of a ring of c subunits within the transmembrane sector of the enzyme. Protons bind to and then are released from the aspartyl-61 residue of subunit c at the center of the membrane. Proton access channels to and from aspartyl-61 are thought to form in subunit a of the F-o sector. Here, we summarize new information on the structural organization of subunit a and the mapping of aqueous accessible residues in the fourth and fifth transmembrane helices (TMHs). Cysteine substituted residues, lying on opposite faces of aTMH-4, preferentially react with either N-ethyl-maleimide (NEM) or Ag+. We propose that aTMH-4 rotates to alternately expose each helical face to aspartyl-61 of subunit c during the proton transport cycle. The concerted helical rotation of aTMH-4 and cTMH-2 are proposed to be coupled to the stepwise mechanical movement of the c-rotor. (C) 2002 Elsevier Science B.V. All rights reserved.
