title: A bacterial arginine-agmatine exchange transporter involved in extreme acid resistance.
abstract: The arginine-dependent extreme acid resistance response of Escherichia coli operates by decarboxylating arginine. AdiC, a membrane antiporter, catalyzes arginine influx coupled to efflux of the decarboxylation product agmatine, effectively exporting a proton in each turnover. Using the adiC coding sequence under control of a tetracycline promoter in an E. coli vector, we expressed and purified the transport-protein with a yield of approximately 10 mg/liter bacterial culture. Glutaraldehyde cross-linking experiments indicate that the protein is a homodimer in detergent micelles and lipid membranes. Purified AdiC reconstituted into liposomes exchanges arginine and agmatine in a strictly coupled, electrogenic fashion. Kinetic analysis yields K(m) approximately 80 microm for Arg, in the same range as its dissociation constant determined by isothermal titration calorimetry.
authors.affiliation: Department of Biochemistry, Howard Hughes Medical Institute, Brandeis University, Waltham, Massachusetts 02454, USA.
authors.forename: Yiling
authors.initials: Y
authors.lastname: Fang
authors.forename: Ludmila
authors.initials: L
authors.lastname: Kolmakova-Partensky
authors.forename: Christopher
authors.initials: C
authors.lastname: Miller
mesh_terms: D000376:Agmatine / Q000737:chemistry*; D026905:Amino Acid Transport Systems / Q000378:metabolism; D017920:Antiporters / Q000378:metabolism; D001120:Arginine / Q000737:chemistry*; D018407:Bacterial Physiological Phenomena; D002384:Catalysis; D003432:Cross-Linking Reagents / Q000494:pharmacology; D019281:Dimerization; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000378:metabolism; D005976:Glutaral / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008055:Lipids / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry; D008823:Micelles; D008954:Models, Biological; D011485:Protein Binding
chemical_list: C476528:AdiC protein, E coli; D026905:Amino Acid Transport Systems; D017920:Antiporters; D003432:Cross-Linking Reagents; D029968:Escherichia coli Proteins; D008055:Lipids; D008081:Liposomes; D008823:Micelles; D000376:Agmatine; D001120:Arginine; D005976:Glutaral