Dynamic mechanisms driving conformational conversions of the β and ε subunits involved in rotational catalysis of F1-ATPase

F-type ATPase is a ubiquitous molecular motor. Investigations on thermophilic F-1-ATPase and its subunits, beta and epsilon, by NMR were reviewed. Using specific isotope labeling, pK(a) of the putative catalytic carboxylate in beta was estimated. Segmental isotope-labeling enabled us to monitor most residues of beta, revealing that the conformational conversion from open to closed form of beta on nucleotide binding found in ATPase was an intrinsic property of beta 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 beta was identical for beta monomer and ATPase, its closed form could be different. ATP-binding was also a critical factor in the conformational conversion of epsilon, an ATP hydrolysis inhibitor. Its structural elucidation was described.