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Viruses are obligate parasites of Eukarya, Archaea and Bacteria. Acanthamoeba polyphaga mimivirus (APMV) is the largest known virus; it grows only in amoeba and is visible under the optical microscope. Mimivirus possesses a 1,185-kilobase double-stranded linear chromosome whose coding capacity is greater than that of numerous bacteria and archaea1, 2, 3.(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)
BACKGROUND 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(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 related(More)
A few duplicated genes have been found useful to root the universal tree of life. Despite controversial results, the consensus led to locate the root in the eubacterial branch. However, we demonstrated (Philippe and Forterre 1999) that all these markers were in fact unsuitable for any firm conclusion, mainly because of their high level of mutational(More)
BACKGROUND Thermococcus gammatolerans was isolated from samples collected from hydrothermal chimneys. It is one of the most radioresistant organisms known amongst the Archaea. We report the determination and annotation of its complete genome sequence, its comparison with other Thermococcales genomes, and a proteomic analysis. RESULTS T. gammatolerans has(More)
The Microviridae comprises icosahedral lytic viruses with circular single-stranded DNA genomes. The family is divided into two distinct groups based on genome characteristics and virion structure. Viruses infecting enterobacteria belong to the genus Microvirus, whereas those infecting obligate parasitic bacteria, such as Chlamydia, Spiroplasma and(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)
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)
Although deoxythymidylate cannot be provided directly by ribonucleotide reductase, the gene encoding thymidylate synthase ThyA is absent from the genomes of a large number of nonsymbiotic microbes. We show that ThyX (Thy1) proteins of previously unknown function form a large and distinct class of thymidylate synthases. ThyX has a wide but sporadic(More)