Identification of a triad of arginine residues in the active site of the ArsC arsenate reductase of plasmid R773.
ArsC from plasmid R773 catalyzes reduction of arsenate in Escherichia coli. Arg-60, Arg-94 and Arg-107 are near the active site residue Cys-12, suggesting that they form an anion binding pocket in the active site and/or participate in catalysis. These three arginine residues were altered to a variety of other residues by site-directed mutagenesis. Only mutants with arginine-to-lysine substitutions conferred arsenate resistance in vivo, although purified R60A, R60E, R60K exhibited varying levels of enzymatic activity. The data support the hypothesis that this triad of arginine residues is involved in arsenate binding and transition-state stabilization.
Department of Biochemistry and Molecular Biology, Wayne State University, School of Medicine, 540 East Canfield Avenue, Detroit, MI 48201, USA.
Jin
J
Shi
Rita
R
Mukhopadhyay
Barry P
BP
Rosen
D001120:Arginine / Q000235:genetics / Q000378:metabolism*; D001149:Arsenates / Q000494:pharmacology; D053501:Arsenite Transporting ATPases; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D016623:Ion Pumps / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D009097:Multienzyme Complexes / Q000737:chemistry / Q000378:metabolism*; D010957:Plasmids / Q000378:metabolism
D001149:Arsenates; D016623:Ion Pumps; D009097:Multienzyme Complexes; D001120:Arginine; D053501:Arsenite Transporting ATPases; C025657:arsenic acid