title: Evidence for two different classes of redox-active cysteines in ribonucleotide reductase of Escherichia coli.
abstract: The large subunit of ribonucleotide reductase from Escherichia coli contains redox-active cysteine residues. In separate experiments, five conserved and 2 nonconserved cysteine residues were substituted with alanines by oligonucleotide-directed mutagenesis. The activities of the mutant proteins were determined in the presence of three different reductants: thioredoxin, glutaredoxin, or dithiothreitol. The results indicate two different classes of redox-active cysteines in ribonucleotide reductase: 1) C-terminal Cys-754 and Cys-759 responsible for the interaction with thioredoxin and glutaredoxin; and 2) Cys-225 and Cys-439 located at the nucleotide-binding site. Our classification of redox-active cysteines differs from the location of the active site cysteines in E. coli ribonucleotide reductase suggested previously (Lin, A.-N. I., Ashley, G. W., and Stubbe, J. (1987) Biochemistry 26, 6905-6909).
authors.affiliation: Department of Molecular Biology, University of Stockholm, Sweden.
authors.forename: A
authors.initials: A
authors.lastname: Aberg
authors.forename: S
authors.initials: S
authors.lastname: Hahne
authors.forename: M
authors.initials: M
authors.lastname: Karlsson
authors.forename: A
authors.initials: A
authors.lastname: Larsson
authors.forename: M
authors.initials: M
authors.lastname: Ormö
authors.forename: A
authors.initials: A
authors.lastname: Ahgren
authors.forename: B M
authors.initials: BM
authors.lastname: Sjöberg
mesh_terms: D000495:Allosteric Site; D001483:Base Sequence; D001665:Binding Sites; D003545:Cysteine; D004229:Dithiothreitol / Q000494:pharmacology; D004926:Escherichia coli / Q000201:enzymology*; D007700:Kinetics; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D009154:Mutation; D009838:Oligodeoxyribonucleotides / Q000138:chemical synthesis; D010084:Oxidation-Reduction; D012264:Ribonucleotide Reductases / Q000235:genetics / Q000378:metabolism*
chemical_list: D046911:Macromolecular Substances; D009838:Oligodeoxyribonucleotides; D012264:Ribonucleotide Reductases; D003545:Cysteine; D004229:Dithiothreitol