|Title||Deleting the IF-likesubunit fromATP synthase is not sufficient to activate ATP hydrolysis.|
|Publication Type||Journal Article|
|Year of Publication||2018|
|Authors||Varghese, F, Blaza, JN, J Y Jones, A, Jarman, OD, Hirst, J|
|Date Published||2018 Jan|
In oxidative phosphorylation, ATP synthases interconvert two forms of free energy: they are driven by the proton-motive force across an energy-transducing membrane to synthesize ATP and displace the ADP/ATP ratio from equilibrium. For thermodynamically efficient energy conversion they must be reversible catalysts. However, in many species ATP synthases are unidirectional catalysts (their rates of ATP hydrolysis are negligible), and in others mechanisms have evolved to regulate or minimize hydrolysis. Unidirectional catalysis byATP synthase has been attributed to its uniquesubunit, which is structurally analogous to the mammalian inhibitor protein IFHere, we used homologous recombination to delete thesubunit from thegenome, and compared ATP synthesis and hydrolysis by the wild-type and knockout enzymes in inverted membrane vesicles and the F-ATPase subcomplex. ATP synthesis was not affected by loss of thesubunit, and the rate of ATP hydrolysis increased by less than twofold, remaining negligible in comparison with the rates of theand mammalian enzymes. Therefore, deleting thesubunit is not sufficient to activate ATP hydrolysis. We close by considering our conclusions in the light of reversible catalysis and regulation in ATP synthase enzymes.
|Alternate Journal||Open Biol|
|PubMed Central ID||PMC5795051|