Interaction of Venturicidin and F_o·F₁-ATPase/ATP Synthase of Tightly Coupled Subbacterial Particles of Paracoccus denitrificans in Energized Membranes

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Tatyana V. Zharova^1,a*, Vladimir S. Kozlovsky², and Vera G. Grivennikova¹

¹Department of Biochemistry, Faculty of Biology, Lomonosov Moscow State University, 119234 Moscow, Russia

²Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119234 Moscow, Russia

^* To whom correspondence should be addressed.

Received April 15, 2022; Revised May 18, 2022; Accepted May 20, 2022

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Proton-translocating F_o⋅F₁-ATPase/synthase that catalyzes synthesis and hydrolysis of ATP is commonly considered to be a reversibly functioning complex. We have previously shown that venturicidin, a specific F_o-directed inhibitor, blocks the synthesis and hydrolysis of ATP with a significant difference in the affinity [Zharova, T. V. and Vinogradov, A. D. (2017) Biochim. Biophys. Acta, 1858, 939-944]. In this paper, we have studied in detail inhibition of F_o⋅F₁-ATPase/synthase by venturicidin in tightly coupled membranes of Paracoccus denitrificans under conditions of membrane potential generation. ATP hydrolysis was followed by the ATP-dependent succinate-supported NAD⁺ reduction (potential-dependent reverse electron transfer) catalyzed by the respiratory chain complex I. It has been demonstrated that membrane energization did not affect the affinity of F_o⋅F₁-ATPase/synthase for venturicidin. The dependence of the residual ATP synthase activity on the concentration of venturicidin approximated a linear function, whereas the dependence of ATP hydrolysis was sigmoidal: at low inhibitor concentrations venturicidin strongly inhibited ATP synthesis without decrease in the rate of ATP hydrolysis. A model is proposed suggesting that ATP synthesis and ATP hydrolysis are catalyzed by two different forms of F_o⋅F₁.

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KEY WORDS: F_o⋅F₁-ATPase/synthase, venturicidin, Paracoccus denitrificans

DOI: 10.1134/S0006297922080065

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