title: A DNA topoisomerase IB in Thaumarchaeota testifies for the presence of this enzyme in the last common ancestor of Archaea and Eucarya.
abstract: DNA topoisomerase IB (TopoIB) was thought for a long time to be a eukaryotic specific enzyme. A shorter version was then found in viruses and later on in several bacteria, but not in archaea. Here, we show that a eukaryotic-like TopoIB is present in the recently sequenced genomes of two archaea of the newly proposed phylum Thaumarchaeota. Phylogenetic analyses suggest that a TopoIB was present in the last common ancestor of Archaea and Eucarya. This finding indicates that the last common ancestor of Archaea and Eucarya may have harboured a DNA genome.
authors.affiliation: Laboratoire de Chimie Bactérienne, Université de Provence, Aix-Marseille I, CNRS UPR9043, IFR88, Marseille, France. celine.brochier@ibsm.cnrs-mrs.fr
authors.forename: Céline
authors.initials: C
authors.lastname: Brochier-Armanet
authors.forename: Simonetta
authors.initials: S
authors.lastname: Gribaldo
authors.forename: Patrick
authors.initials: P
authors.lastname: Forterre
mesh_terms: D001105:Archaea / Q000201:enzymology*; D001419:Bacteria / Q000201:enzymology; D004264:DNA Topoisomerases, Type I / Q000737:chemistry / Q000235:genetics*; D005057:Eukaryotic Cells / Q000201:enzymology*; D016013:Likelihood Functions; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D014780:Viruses / Q000201:enzymology
chemical_list: D004264:DNA Topoisomerases, Type I