REVIEW: F_o·F₁ ATP-synthase/ATPase of Paracoccus denitrificans: Mystery of Unidirectional Catalysis

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Tatiana V. Zharova^1,a*, Vera G. Grivennikova¹

¹Department of Biochemistry, Faculty of Biology, Lomonosov Moscow State University, 119991 Moscow, Russia

^* To whom correspondence should be addressed.

Received: August 28, 2024; Revised: September 24, 2024; Accepted: October 16, 2024

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F_o·F₁ ATP synthases/ATPases (F_o·F₁) catalyze ATP synthesis by consuming energy of electrochemical potential of hydrogen ions (pmf), or ATP hydrolysis resulting in the pmf formation. It is generally accepted to consider F_o·F₁ as a reversible chemomechanical-electrical molecular machine, however: (i) the mechanism of energy-dependent ATP synthesis is based only on the data on hydrolytic activity of the enzyme, (ii) F_o·F₁ from a number of organisms effectively synthesize, but is unable to hydrolyze ATP, which indicates non-observance of the principle of microreversibility and requires development of a new hypotheses concerning the enzyme mechanism. Since 1980, the group of A. D. Vinogradov has been developing a concept according to which the elementary catalysis stages of ATP hydrolysis and ATP synthesis do not coincide, and there are two independently operating forms of F_o·F₁ in the coupled membranes – pmf-generating ATPase and pmf-consuming ATP synthase. F_o·F₁ of P. denitrificans as a natural model of an irreversibly functioning enzyme is a convenient object for experimental verification of the hypothesis of unidirectional energy conversion. The review considers modern concepts of the molecular mechanisms of regulation of F_o·F₁ ATP synthase/ATPase of P. denitrificans and development of the hypothesis of two forms of F_o·F₁.

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KEY WORDS: F_o·F₁ ATP synthase/ATPase, Paracoccus denitrificans, unidirectional enzyme catalysis

DOI: 10.1134/S000629792460399X

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