[Character of K+ absorption and its interaction with membrane protein pumps in Escherichia coli, grown under anaerobic conditions in the presence of nitrate].

The character of H(+)-K(+)-exchange in E.coli, grown in anaerobic conditions in the presence of sodium nitrate and performed a nitrate respiration, has been studied. The K+ uptake has been shown to occur by one step, to be not inhibited by N,N'-dicyclohexylcarbodiimide, but to be stopped by arsenate and protonophore. It has K(m) of 4.5 mM, K+ accumulation in cell is more than 200 mM and K+ distribution between the cytoplasm and the medium is more than 10(3) (K+ equilibrium potential is achieved 190 mV). To switch on a mechanism of K+ uptake is depended on osmotic shock and carried out upon positive as well as negative shocks in spheroplasts. A H+ efflux occurs with constant rate while glucose is in the medium and a stoichiometry for the initial H+ to K+ fluxes is variable upon a different experimental conditions. In spite of H(+)-K(+)-exchange in anaerobically grown E.coli, a production of H2 in bacteria is not observed, an ATPase activity of isolated membranes sensitive, to N,N'-dicyclohexylcarbodiimide is not stimulated by K+ and lost in E.coli mutant with an unc-deletion. It is concluded that H+ and K+ transfer through the membranes in E.coli performed a nitrate respiration, occur through different systems-a respiration chain and the TrkA system of K+ uptake. The latest operates itself, has no ATPase activity and interacts with membrane proton pumps indirectly using transmembrane proton gradient (delta mu H+) as a driving force as well as ATP as a regulator of activity. A sensitivity of this system to osmotic shock is lost under destruction of periplasmic space.