This article is part of a series on Origin and early evolution of life, edited by Dr Eugene V Koonin.

Discovery notes

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

Céline Brochier-Armanet¹ , Simonetta Gribaldo² and Patrick Forterre^2,3

¹  Université de Provence, Aix-Marseille I, CNRS UPR9043, Laboratoire de Chimie Bactérienne, IFR88, Marseille, France

²  Institut Pasteur, 25 rue du Docteur roux, 75015 Paris, France

³  Univ Paris-sud, Institut de Génétique et Microbiologie, CNRS UMR8621, 91405 Orsay Cedex, France

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Biology Direct 2008, 3:54doi:10.1186/1745-6150-3-54

Published:	23 December 2008

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.

Reviewer

This article was reviewed by Eugene Koonin and Anthony Poole