A second class I ribonucleotide reductase in Enterobacteriaceae: Characterization of the Salmonella typhimurium enzyme

Albert Jordan, Elisabet Pontis, Mohamed Atta, Maria Krook, Isidre Gibert, Jordi Barbé, Peter Reichard

Research output: Contribution to journalArticleResearchpeer-review

93 Citations (Scopus)

Abstract

The nrdA and nrdB genes of Escherichia coli and Salmonella typhimurium encode the R1 and R2 proteins that together form an active class I ribonucleotide reductase. Both organisms contain two additional chromosomal genes, nrdE and nrdF, whose corresponding protein sequences show some homology to the products of the genes nrdA and nrdB. When present on a plasmid, nrdE and nrdF together complement mutations in nrdA or nrdB. We have now obtained in nearly homogeneous form the two proteins encoded by the S. typhimurium nrdE and nrdF genes (R1E and R2F). They correspond to the R1 and R2 proteins. Each protein is a homodimer. Together they catalyze the reduction of CDP to dCDP, using dithiothreitol or reduced glutaredoxin, but not thioredoxin, as an electron donor. CDP reduction is strongly stimulated by low concentrations of dATP, presumably acting as an allosteric effector. Protein R2F contains an antiferromagnetically coupled dinuclear iron center and a tyrosyl free radical. The E. coli and S. typhimurium chromosome thus have maintained the information for a potentially active additional class I ribonucleotide reductase, whose role in vivo is as yet unknown. The allosteric regulation of this enzyme differs from that of the normally expressed reductase.
Original languageEnglish
Pages (from-to)12892-12896
JournalProceedings of the National Academy of Sciences of the United States of America
Volume91
Issue number26
DOIs
Publication statusPublished - 20 Dec 1994

Keywords

  • deoxyribonucleotide synthesis
  • glutaredoxin
  • iron center
  • tyrosyl radical

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