title: Characterization of the adenosine triphosphatase activity of the periplasmic histidine permease, a traffic ATPase (ABC transporter).
abstract: The superfamily of traffic ATPases (ABC transporters) includes bacterial periplasmic transport systems (permeases) and eukaryotic transporters. The histidine permease of Salmonella typhimurium is composed of a membrane-bound complex (HisQMP2) containing four subunits, and of a soluble receptor, the histidine-binding protein (HisJ). Transport is energized by ATP. In this article the ATPase activity of HisQMP2 has been characterized, using a novel assay that is independent of transport. The assay uses Mg2+ ions to permeabilize membrane vesicles or proteoliposomes, thus allowing access of ATP to both sides of the bilayer. HisQMP2 displays a low level of intrinsic ATPase activity in the absence of HisJ; unliganded HisJ stimulates the activity and liganded HisJ stimulates to an even higher level. All three levels of activity display positive cooperativity for ATP with a Hill coefficient of 2 and a K0. 5 value of 0.6 mM. The activity has been characterized with respect to pH, salt, phospholipids, substrate, and inhibitor specificity. Free histidine has no effect. The activity is inhibited by orthovanadate, but not by N-ethylmaleimide, bafilomycin A1, or ouabain. Several nucleotide analogs, ADP, 5'-adenylyl-beta, gamma-imidodiphosphate, adenosine 5'-(beta,gammaimino)triphosphate, and adenosine 5'-O-(3-thio)triphosphate, inhibit the activity. Unliganded HisJ does not compete with liganded HisJ for the stimulation of the ATPase activity of HisQMP2.
authors.affiliation: Department of Molecular and Cell Biology, Division of Biochemistry and Molecular Biology, University of California, Berkeley, California 94720, USA.
authors.forename: C E
authors.initials: CE
authors.lastname: Liu
authors.forename: P Q
authors.initials: PQ
authors.lastname: Liu
authors.forename: G F
authors.initials: GF
authors.lastname: Ames
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000378:metabolism*; D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D026923:Amino Acid Transport Systems, Basic; D001426:Bacterial Proteins / Q000378:metabolism; D001667:Binding, Competitive; D001693:Biological Transport, Active; D002352:Carrier Proteins / Q000378:metabolism; D004926:Escherichia coli; D006639:Histidine / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D008274:Magnesium / Q000378:metabolism; D008278:Magnesium Sulfate / Q000494:pharmacology; D026901:Membrane Transport Proteins / Q000378:metabolism*; D033902:Periplasmic Binding Proteins; D012486:Salmonella typhimurium; D012965:Sodium Chloride / Q000494:pharmacology
chemical_list: D018528:ATP-Binding Cassette Transporters; D026923:Amino Acid Transport Systems, Basic; D001426:Bacterial Proteins; D002352:Carrier Proteins; D026901:Membrane Transport Proteins; D033902:Periplasmic Binding Proteins; C018963:histidine-binding protein; D012965:Sodium Chloride; D006639:Histidine; C043828:histidine permease, Bacteria; D008278:Magnesium Sulfate; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; D008274:Magnesium