ELECTROCHEMICAL STUDY OF ENERGY-DEPENDENT POTASSIUM ACCUMULATION IN ESCHERICHIA-COLI .4. REGULATION OF THE H+-K+-PUMP OPERATION BY A PERIPLASMIC PROTEIN

The principle of regulation of the H+-K+-pump operation in E. coli cells by means of a specific periplasmic protein is developed. It is supposed that the H+-K+-pump of the Gram-negative bacterium consists of three basic parts: ATP-ase located on the inside of plasma membrane; proteolipid which serves as a transmembrane ionic channel and connects F1 with periplasmic space, and finally a protein-valve which associates with the exterior of Fo and falls between Fo and the polysaccharide portion of a cell wall. The variation in a size of periplasmic space according to cell volume can compress and strain the PV opening and blocking the outdoor of Fo. Such a regulation of pump operation is actuated by osmolality in the external medium. Some effects and experimental evidence are discussed as well. © 1979.