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The archaeal domain is currently divided into two major phyla, the Euryarchaeota and Crenarchaeota. During the past few years, diverse groups of uncultivated mesophilic archaea have been discovered and affiliated with the Crenarchaeota. It was recently recognized that these archaea have a major role in geochemical cycles. Based on the first genome sequence(More)
Type II topoisomerases help regulate DNA topology during transcription, replication and recombination by catalysing DNA strand transfer through transient double-stranded breaks. All type II topoisomerases described so far are members of a single protein family. We have cloned and sequenced the genes encoding the A and B subunits of topoisomerase II from the(More)
Cultivable archaeal species are assigned to two phyla - the Crenarchaeota and the Euryarchaeota - by a number of important genetic differences, and this ancient split is strongly supported by phylogenetic analysis. The recently described hyperthermophile Nanoarchaeum equitans, harboring the smallest cellular genome ever sequenced (480 kb), has been(More)
Several composite universal trees connected by an ancestral gene duplication have been used to root the universal tree of life. In all cases, this root turned out to be in the eubacterial branch. However, the validity of results obtained from comparative sequence analysis has recently been questioned, in particular, in the case of ancient phylogenies. For(More)
DNA viruses of the Archaea have highly diverse and often exceptionally complex morphotypes. Many have been isolated from geothermally heated hot environments, raising intriguing questions about their origins, and contradicting the widespread notion of limited biodiversity in extreme environments. Here, we provide a unifying view on archaeal viruses, and(More)
  • P Forterre
  • 1995
All thermophiles discovered so far are prokaryotes (Bacteria or Archaea). Furthermore, reconstructions of rRNA phylogenies suggest that the progenitor of all prokaryotes was a thermophile. These data are usually interpreted as supporting the hypothesis that all present day organisms, including eukaryotes, originated from hyperthermophiles. However, this(More)
A phylogenetic analysis of the five major families of DNA polymerase is presented. Viral and plasmid sequences are included in this compilation along with cellular enzymes. The classification by Ito and Braithwaite (Ito and Braithwaite 1991) of the A, B, C, D, and X families has been extended to accommodate the ``Y family'' of DNA polymerases that are(More)
Enrichments for anaerobic organotrophic hyperthermophiles were performed with hydrothermal chimney samples collected at the Guaymas Basin (27 degrees 01' N, 111 degrees 24' W). Positive enrichments were submitted to gamma-irradiation at a dose of 30 kGy. One of the resistant strains, designated strain EJ3(T), formed regular motile cocci. The new strain grew(More)
The idea that hyperthermophiles are in some way ar-Centre National de la Recherche Scientifique chaic has been favored by most workers in their interpre-Bâ timent 409 tations of experimental data. For example, the apparent Université Paris-Sud absence of specific glycolytic enzymes in hyperther-91405 Orsay-Cedex mophilic archaea has led to the suggestion(More)
Despite a rapid increase in the amount of available archaeal sequence information, little is known about the duplication of genetic material in the third domain of life. We identified a single origin of bidirectional replication in Pyrococcus abyssi by means of in silico analyses of cumulative oligomer skew and the identification of an early replicating(More)