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

Abstract

F-type ATPase is a ubiquitous molecular motor. Investigations on thermophilic F1-ATPase and its subunits, β and ε, by NMR were reviewed. Using specific isotope labeling, pKa 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.

Mechanism of ATP hydrolysis dependent rotation of ATP synthases

“…Cryo-grids were prepared using a reaction mixture of ND-FoF1, containing 26 The two F1 domain 80˚ structures were obtained from 56 k particles using an αDβD covering mask (Extended Data Fig. 2b).…”

“…9d). One of the driving events for this structural transition is the conformational change from the ATP-bound α E β E to the more closed α T β T , which can be explained by a zipper motion of α E β E occurring upon ATP binding 26 . Our structural analysis indicates that the ATP bound to α T β T is hydrolyzed as a result of the conformational change from α T β T to α D β D which occurs just after the 80° rotation angle (81° to 83°) (Fig.…”

Characterization of regulatory central stalk epitopes of mycobacterial- and acetogen F-ATP synthases

“…The catalytic events that lead to the enzymatic cleavage of the γ-phosphate bond of ATP are elucidated to great detail (167,168,173), however here a general overview will be provided.…”

“…In addition, mycobacterial F-ATP synthase is characterized by low capacity for ATP hydrolysis, owing to this trait to several adaptations present exclusively in this enzyme (2). One such adaptation is a loop comprised of 14 amino acids of γ [166][167][168][169][170][171][172][173][174][175][176][177][178][179] epitope whose deletion from the genome of M. smegmatis caused an increase in ATPase activity, ATP-driven proton translocation and a significant reduction of ATP synthesis (206). These experiments marked the γ 166-179 loop as an inhibitor of ATP consumption coupled to the generation of the proton-motive force and described it as a conditionally unidirectional "proton-tight" seal, present only in mycobacterial F-ATP synthases.…”

Structure and regulation of the mycobacterial F1-ATPase

“…To allow for the release of ADP and Pi, the γ-phosphate bond is cleaved and in turn, the βsubunit undergoes another conformational change, leading to the βDP conformation [184].…”