Regulation of expression of Na+-translocating NADH: quinone oxidoreductase genes in Vibrio harveyi and Klebsiella pneumoniae

The expression of genes encoding sodium-translocating NADH:quinone oxidoreductase (Na+-NQR) was studied in the marine bacterium Vibrio harveyi and in the enterobacterium Klebsiella pneumoniae. It has been shown that such parameters as NaCl concentration, pH value, and presence of an uncoupler in the growth media do not influence significantly the level of nqr expression. However, nqr expression depends on the growth substrates used by these bacteria. Na+-NQR is highly repressed in V. harveyi during anaerobic growth, and nqr expression is modulated by electron acceptors and values of their redox potentials. The latter effect was shown to be independent of the ArcAB regulatory system.