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

FEBS Lett. 2003 Nov 27;555(1):29-34. doi: 10.1016/s0014-5793(03)01101-3.

Abstract

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.

Publication types

  • Research Support, U.S. Gov't, P.H.S.
  • Review

MeSH terms

  • Bacterial Proton-Translocating ATPases / chemistry*
  • Bacterial Proton-Translocating ATPases / metabolism*
  • Escherichia coli / enzymology
  • Models, Molecular
  • Protein Folding
  • Protein Structure, Secondary
  • Protein Subunits
  • Proton-Motive Force
  • Rotation
  • Water / chemistry

Substances

  • Protein Subunits
  • Water
  • Bacterial Proton-Translocating ATPases