Probing the rotor subunit interface of the ATP synthase from Ilyobacter tartaricus

摘要: The interaction between the c(11)ring and gammaepsilon complex, forming rotor of Ilyobacter tartaricus ATP synthase, was probed by surface plasmon resonance spectroscopy in vitro reconstitution analysis. results provide, for first time, a direct quantitative assessment stability rotor. data indicated very tight binding with an apparent K(d) value approximately 7.4nm. assembly primarily dependent on cring gammasubunit, to free epsilon subunit not observed. Mutagenesis selected conserved amino acid residues all three components (cR45, cQ46, gammaE204, gammaF203 epsilonH38) severely affected assembly. kinetics complex mutants suggested that c(11)gammaepsiloncomplex governed interactions low high affinity. Low-affinity observed polar loops subunits bottom part gamma subunit. High-affinity interactions, involving two gammaE204 epsilonH38, stabilized holo-c(11)gammaepsilon complex. NMR experiments acquisition conformational order otherwise flexible C- N-terminal regions this study suggest docking central stalk F(1)complex ring F(o) form tight, but reversible, contacts provides explanation relative ease dissociation F(1)F(o)complexes.