Jarman OD, Biner O, Hirst J. Regulation of ATP hydrolysis by the ε subunit, ζ subunit and Mg-ADP in the ATP synthase of Paracoccus denitrificans.
Biochim Biophys Acta Bioenerg 2020;
1862:148355. [PMID:
33321110 PMCID:
PMC8039183 DOI:
10.1016/j.bbabio.2020.148355]
[Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Figures] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 11/27/2020] [Accepted: 12/08/2020] [Indexed: 12/17/2022]
Abstract
F1FO-ATP synthase is a crucial metabolic enzyme that uses the proton motive force from respiration to regenerate ATP. For maximum thermodynamic efficiency ATP synthesis should be fully reversible, but the enzyme from Paracoccus denitrificans catalyzes ATP hydrolysis at far lower rates than it catalyzes ATP synthesis, an effect often attributed to its unique ζ subunit. Recently, we showed that deleting ζ increases hydrolysis only marginally, indicating that other common inhibitory mechanisms such as inhibition by the C-terminal domain of the ε subunit (ε-CTD) or Mg-ADP may be more important. Here, we created mutants lacking the ε-CTD, and double mutants lacking both the ε-CTD and ζ subunit. No substantial activation of ATP hydrolysis was observed in any of these strains. Instead, hydrolysis in even the double mutant strains could only be activated by oxyanions, the detergent lauryldimethylamine oxide, or a proton motive force, which are all considered to release Mg-ADP inhibition. Our results establish that P. denitrificans ATP synthase is regulated by a combination of the ε and ζ subunits and Mg-ADP inhibition.
Collapse