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Publication Abstract from PubMed

The Acinetobacter baumannii F(1) F(O) -ATP synthase (alpha(3) :beta(3) :gamma:delta:epsilon:a:b(2) :c(10) ), which is essential for this strictly respiratory opportunistic human pathogen, is incapable of ATP-driven proton translocation due to its latent ATPase activity. Here, we generated and purified the first recombinant A. baumannii F(1) -ATPase (AbF(1) -ATPase) composed of subunits alpha(3) :beta(3) :gamma:epsilon, showing latent ATP hydrolysis. A 3.0 A cryo-electron microscopy structure visualizes the architecture and regulatory element of this enzyme, in which the C-terminal domain of subunit epsilon (Abepsilon) is present in an extended position. An epsilon-free AbF(1) -abetagamma complex generated showed a 21.5-fold ATP hydrolysis increase, demonstrating that Abepsilon is the major regulator of AbF(1) -ATPase's latent ATP hydrolysis. The recombinant system enabled mutational studies of single amino acid substitutions within Abepsilon or its interacting subunits beta and gamma, respectively, as well as C-terminal truncated mutants of Abepsilon, providing a detailed picture of Abepsilon's main element for the self-inhibition mechanism of ATP hydrolysis. Using a heterologous expression system, the importance of Abepsilon's C-terminus in ATP synthesis of inverted membrane vesicles, including AbF(1) F(O) -ATP synthases, has been explored. In addition, we are presenting the first NMR solution structure of the compact form of Abepsilon, revealing interaction of its N-terminal beta-barrel and C-terminal a-hairpin domain. A double mutant of Abepsilon highlights critical residues for Abepsilon's domain-domain formation which is important also for AbF(1) -ATPase's stability. Abepsilon does not bind MgATP, which is described to regulate the up and down movements in other bacterial counterparts. The data are compared to regulatory elements of F(1) -ATPases in bacteria, chloroplasts, and mitochondria to prevent wasting of ATP.

Atomic insights of an up and down conformation of the Acinetobacter baumannii F(1) -ATPase subunit epsilon and deciphering the residues critical for ATP hydrolysis inhibition and ATP synthesis.,Saw WG, Le KCM, Shin J, Kwek JHM, Wong CF, Ragunathan P, Fong TC, Muller V, Gruber G FASEB J. 2023 Jul;37(7):e23040. doi: 10.1096/fj.202300175RR. PMID:37318822^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.