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

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