title: Ribonucleotide reductase in the archaeon Pyrococcus furiosus: a critical enzyme in the evolution of DNA genomes?
abstract: Ribonucleotide reductase (RNR), the enzyme responsible for deoxyribonucleotide synthesis, has been isolated from Pyrococcus furiosus, a deeply branching hyperthermophilic, strictly anaerobic archaeon. Its gene has been cloned, sequenced, and shown to harbor two insertions encoding inteins. The purified enzyme absolutely requires adenosylcobalamin for activity, a trait that defines it as a member of class II (adenosyl-cobalamin-dependent) prokaryotic RNRs. On the other hand, the archaeal RNR has significant amino acid sequence homology with class I (aerobic non-heme iron-dependent) and class III (anaerobic iron-sulfur-dependent) RNRs present in eukaryotes and bacteria, respectively. It is proposed that this enzyme may be the closest possible relative of the original RNR, which allowed the key "RNA world" to "DNA world" transition, and that the different classes of present-day RNRs are the products of divergent evolution.
authors.affiliation: Laboratoire d'Etudes Dynamiques et Structurales de la Sélectivité, Unité Mixte de Recherches Centre National de la Recherche Scientifique 5616, Université, Joseph Fourier, Grenoble, France.
authors.forename: J
authors.initials: J
authors.lastname: Riera
authors.forename: F T
authors.initials: FT
authors.lastname: Robb
authors.forename: R
authors.initials: R
authors.lastname: Weiss
authors.forename: M
authors.initials: M
authors.lastname: Fontecave
mesh_terms: D000595:Amino Acid Sequence; D001105:Archaea / Q000201:enzymology*; D005075:Biological Evolution; D003545:Cysteine / Q000737:chemistry; D004247:DNA / Q000235:genetics; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D012313:RNA / Q000235:genetics; D012264:Ribonucleotide Reductases / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D012313:RNA; D004247:DNA; D012264:Ribonucleotide Reductases; D003545:Cysteine