Cys377 Residue in NqrF Subunit Confers Ag⁺ Sensitivity of Na⁺-Translocating NADH:quinone Oxidoreductase from Vibrio harveyi

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M. S. Fadeeva¹, Y. V. Bertsova¹, L. Euro², and A. V. Bogachev^1*

¹Department of Molecular Energetics of Microorganisms, Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119992 Moscow, Russia; fax: (495) 939-0338; E-mail: bogachev@genebee.msu.su

²Research Program of Molecular Neurology, Biomedicum-Helsinki, University of Helsinki, Haartmaninkatu 8, 00290 Helsinki, Finland; E-mail: Liliya.Euro@helsinki.fi

^* To whom correspondence should be addressed.

Received August 16, 2010; Revision received October 8, 2010

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The Na⁺-translocating NADH:quinone oxidoreductase (Na⁺-NQR) is a component of the respiratory chain of various bacteria that generates a redox-driven transmembrane electrochemical Na⁺ potential. The Na⁺-NQR activity is known to be specifically inhibited by low concentrations of silver ions. Replacement of the conserved Cys377 residue with alanine in the NqrF subunit of Na⁺-NQR from Vibrio harveyi resulted in resistance of the enzyme to Ag⁺ and to other heavy metal ions. Analysis of the catalytic activity also showed that the rate of electron input into the mutant Na⁺-NQR decreased by about 14-fold in comparison to the wild type enzyme, whereas all other properties of _NqrFC377A Na⁺-NQR including its stability remained unaffected.

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KEY WORDS: Na⁺-translocating NADH:quinone oxidoreductase, NqrF, ferredoxin:NADP⁺ oxidoreductase, sensitivity to heavy metals, protein stability

DOI: 10.1134/S0006297911020040

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