Dynamic mechanisms driving conformational conversions of the β and ε subunits involved in rotational catalysis of F-ATPase.

F-type ATPase is a ubiquitous molecular motor. Investigations on thermophilic F-ATPase and its subunits, β and ε, by NMR were reviewed. Using specific isotope labeling, pK of the putative catalytic carboxylate in β was estimated. Segmental isotope-labeling enabled us to monitor most residues of β, revealing that the conformational conversion from open to closed form of β on nucleotide binding found in ATPase was an intrinsic property of β and could work as a driving force of the rotational catalysis. A stepwise conformational change was driven by switching of the hydrogen bond networks involving Walker A and B motifs. Segmentally labeled ATPase provided a well resolved NMR spectra, revealing while the open form of β was identical for β monomer and ATPase, its closed form could be different. ATP-binding was also a critical factor in the conformational conversion of ε, an ATP hydrolysis inhibitor. Its structural elucidation was described.