ИСТИНА

M.S. Muntyan and coworkers [1] in our group succeeded in describing Na + - motive terminal oxidase from the extremely alkalophilic bacterium Thioalkalivibrio versutus living in alkaline Siberian soda lakes at saturating salt concentration. At such conditions, this respiring bacterium cannot employ Mitchellian H+ cycle because two constituents of proton motive force, Δψ and ΔpH, are oppositely directed. It was found that (i) respiration and Δψ in Th. vesutus show pH optimum at pH 9, (ii) both respiration and Δψ at this pH are stimulated by Na+, whereas K +, Li+ and choline+ are ineffective, (iii) respiration is coupled to extrusion of Na+ from the cell or right-side out vesicles, the extrusion being stimulated by protonophorous uncouplers, (iv) Paracoccus denitrificans mutant lacking all terminal oxidases and displaying no respiration-driven Na+ pumping became capable of such a pumping after expression of Th. versutus cbb3. The above listed data directly demonstrated for the first time the existence of a terminal oxidase pumping Na+ instead of H+.