Both lobes of the soluble receptor of the periplasmic histidine permease, an ABC transporter (traffic ATPase), interact with the membrane-bound complex. Effect of different ligands and consequences for the mechanism of action.
The histidine permease of Salmonella typhimurium is an ABC transporter (traffic ATPase). The liganded soluble receptor, the histidine-binding protein HisJ, interacts with the membrane-bound complex HisQMP2 and stimulates its ATPase activity, which results in histidine translocation. In this study, we utilized HisJ proteins with mutations in either of the two lobes and wild type HisJ liganded with different substrates to show that each lobe carries an interaction site and that both lobes are involved in inducing (stimulating) the ATPase activity. We suggest that the spatial relationship between the lobes is one of the factors recognized by the membrane-bound complex in dictating the efficiency of the induction signal and of translocation. Several of the key residues involved have been identified. In addition, using constitutive ATPase mutants, we show that the binding protein provides some additional essential function(s) in translocation that is independent of the stimulation of ATP hydrolysis, and one possible mechanism is proposed, which includes the notion that liganded HisJ has different optimal conformations for signaling and for translocation.
Liu
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CE
Department of Molecular and Cell Biology, Division of Biochemistry and Molecular Biology, University of California, Berkeley, California 94720, USA.
Liu
P Q
PQ
Wolf
A
A
Lin
E
E
Ames
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GF
D018528:ATP-Binding Cassette Transporters; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D026923:Amino Acid Transport Systems, Basic; D001426:Bacterial Proteins; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D004790:Enzyme Induction; D006868:Hydrolysis; D008024:Ligands; D026901:Membrane Transport Proteins / Q000378:metabolism*; D016296:Mutagenesis; D019897:Periplasm / Q000201:enzymology*; D033902:Periplasmic Binding Proteins; D011485:Protein Binding; D012486:Salmonella typhimurium / Q000201:enzymology
D018528:ATP-Binding Cassette Transporters; D026923:Amino Acid Transport Systems, Basic; D001426:Bacterial Proteins; D002352:Carrier Proteins; D008024:Ligands; D026901:Membrane Transport Proteins; D033902:Periplasmic Binding Proteins; C018963:histidine-binding protein; C043828:histidine permease, Bacteria; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases