Oxidative Phosphorylation and Respiratory Control Phenomenon in Paracoccus denitrificans Plasma Membrane

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T. V. Zharova and A. D. Vinogradov^*

Department of Biochemistry, Faculty of Biology, Lomonosov Moscow State University, 119992 Moscow, Russia; fax: (495) 939-1376; E-mail: adv@biochem.bio.msu.su

^* To whom correspondence should be addressed.

Received April 18, 2012; Revision received June 1, 2012

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Changes in respiratory activity, transmembrane electric potential, and ATP synthesis as induced by additions of limited amounts of ADP and P_i to tightly coupled inverted (inside-out) Paracoccus denitrificans plasma membrane vesicles were traced. The pattern of the changes was qualitatively the same as those observed for coupled mitochondria during the classical State 4–State 3–State 4 transition. Bacterial vesicles devoid of energy-dependent permeability barriers for the substrates of oxidation and phosphorylation were used as a simple experimental model to investigate two possible mechanisms of respiratory control: (i) in State 4 phosphoryl transfer potential (ATP/ADP × P_i) is equilibrated with proton-motive force by reversibly operating F₁·F_o-ATPase (thermodynamic control); (ii) in State 4 apparent “equilibrium” is reached by unidirectional operation of proton motive force-activated F₁·F_o-ATP synthase. The data support the kinetic mechanism of the respiratory control phenomenon.

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KEY WORDS: F_oF₁-H⁺-ATP synthase, oxidative phosphorylation, bacterial plasma membrane, Paracoccus denitrificans

DOI: 10.1134/S0006297912090064

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