title: The high-affinity K+-translocating ATPase complex from Bacillus acidocaldarius consists of three subunits.
abstract: Cells of the thermoacidophilic bacterium Bacillus acidocaldarius express a high-affinity K+-uptake system when grown at low external K+. A vanadate-sensitive, K+- and Mg2+-stimulated ATPase was partially purified from membranes of these cells by solubilization with a non-ionic detergent followed by ion-exchange chromatography of the extract. Combinations of non-denaturing and denaturing electrophoretic separation methods revealed that the ATPase complex consisted of three subunits with molecular weights almost identical to those of the KdpA, B and C proteins, which together form the Kdp high-affinity, K+-translocating ATPase complex of Escherichia coli. The affinity of the partially purified ATPase from B. acidocaldarius for its substrates K+ (Km 2-3 microM) and ATP (Km 80 microM), its stimulation by various divalent cations, and its inhibition by vanadate (Ki 1-2 microM), bafilomycin A1 (Ki 20 microM), DCCD (Ki 200 microM) or Ca2+ were also similar to those of the E. coli enzyme, indicating that the two K+-translocating ATPases have almost identical properties.
authors.affiliation: Abteilung Mikrobiologie, Universität Osnabrück, FRG.
authors.forename: J
authors.initials: J
authors.lastname: Hafer
authors.forename: A
authors.initials: A
authors.lastname: Siebers
authors.forename: E P
authors.initials: EP
authors.lastname: Bakker
mesh_terms: D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism*; D001407:Bacillus / Q000201:enzymology* / Q000378:metabolism; D015153:Blotting, Western; D027682:Cation Transport Proteins; D002462:Cell Membrane / Q000201:enzymology; D002852:Chromatography, Ion Exchange; D045424:Complex Mixtures; D003429:Cross Reactions; D003902:Detergents; D015180:Electrophoresis, Gel, Two-Dimensional; D013293:Enterococcus faecalis / Q000201:enzymology; D004926:Escherichia coli / Q000201:enzymology; D029968:Escherichia coli Proteins; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D010455:Peptides / Q000032:analysis; D011188:Potassium / Q000378:metabolism*; D011487:Protein Conformation; D012995:Solubility; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D027682:Cation Transport Proteins; D045424:Complex Mixtures; D003902:Detergents; D029968:Escherichia coli Proteins; D010455:Peptides; C054295:aminoxide WS 35; D000251:Adenosine Triphosphatases; C058166:potassium translocating Kdp-ATPase, E coli; C022761:potassium transporting ATPase; D011188:Potassium