A DNA topoisomerase IB in Thaumarchaeota testifies for the presence of this enzyme in the last common ancestor of Archaea and Eucarya.

Céline Brochier-Armanet (1) , Simonetta Gribaldo (2) , Patrick Forterre (2, 3)

1 LCB - Laboratoire de chimie bactérienne
2 BMGE - Biologie Moléculaire du Gène chez les Extrêmophiles
3 IGM - Institut de génétique et microbiologie [Orsay]

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.

Domaines: Biochimie, Biologie Moléculaire; Microbiologie et Parasitologie

Céline Brochier-Armanet, Simonetta Gribaldo, Patrick Forterre. A DNA topoisomerase IB in Thaumarchaeota testifies for the presence of this enzyme in the last common ancestor of Archaea and Eucarya.. Biol Direct, 2008, 3, pp.54. ⟨10.1186/1745-6150-3-54⟩. ⟨hal-00353347⟩