High-resolution structure of the rotor ring of a proton-dependent ATP synthase

Nat Struct Mol Biol. 2009 Oct;16(10):1068-73. doi: 10.1038/nsmb.1678. Epub 2009 Sep 27.


The crystal structure of the c-ring from the proton-coupled F1Fo ATP synthase from Spirulina platensis is shown at 2.1-A resolution. The ring includes 15 membrane-embedded c subunits forming an hourglass-shaped assembly. The structure demonstrates that proton translocation across the membrane entails protonation of a conserved glutamate located near the membrane center in the c subunit outer helix. The proton is locked in this site by a precise hydrogen bond network reminiscent of that in Na+-dependent ATP synthases. However, the structure suggests that the different coordination chemistry of the bound proton and the smaller curvature of the outer helix drastically enhance the selectivity of the H+ site against other cations, including H3O+. We propose a model for proton translocation whereby the c subunits remain in this proton-locked state when facing the membrane lipid. Proton exchange would occur in a more hydrophilic and electrostatically distinct environment upon contact with the a subunit interface.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacterial Proton-Translocating ATPases / chemistry*
  • Bacterial Proton-Translocating ATPases / genetics*
  • Binding Sites
  • Biological Transport
  • Cations
  • Ions
  • Lipids / chemistry
  • Molecular Conformation
  • Molecular Sequence Data
  • Protein Structure, Tertiary
  • Protons
  • Sequence Homology, Amino Acid
  • Sodium / chemistry
  • Spirulina / enzymology*
  • Spirulina / genetics
  • Static Electricity


  • Cations
  • Ions
  • Lipids
  • Protons
  • Sodium
  • Bacterial Proton-Translocating ATPases

Associated data

  • PDB/2WIE