Ribonucleotide reductase in the archaeon Pyrococcus furiosus: A critical enzyme in the evolution of DNA genomes?

Ribonucleotide reductase in the archaeon Pyrococcus furiosus: A critical enzyme in the evolution of DNA genomes?

^*Laboratoire d’Etudes Dynamiques et Structurales de la Sélectivité, Unité Mixte de Recherches Centre National de la Recherche Scientifique 5616, Université Joseph Fourier, BP53, 38041 Grenoble Cedex 9, France; ^†Center of Marine Biotechnology, University of Maryland Biotechnology Institute, Baltimore, MD 21202; and ^‡Department of Genetics, University of Utah, Salt Lake City, UT 84112

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 (adenosylcobalamin-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.

Footnotes

↵ § To whom reprint requests should be addressed. e-mail: Marc.Fontecave{at}ujf-grenoble.fr.
Peter Reichard, Karolinska Institute, Stockholm, Sweden
Abbreviations: RNR, ribonucleotide reductase; AdoCbl, adenosylcobalamin.

Data deposition: The sequence reported in this paper has been deposited in the dbEST data base (accession no. U78098U78098).