A new example of viral intein in Mimivirus.
BACKGROUND
Inteins are "protein introns" that remove themselves from their host proteins through an autocatalytic protein-splicing. After their discovery, inteins have been quickly identified in all domains of life, but only once to date in the genome of a eukaryote-infecting virus.


RESULTS
Here we report the identification and bioinformatics characterization of an intein in the DNA polymerase PolB gene of amoeba infecting Mimivirus, the largest known double-stranded DNA virus, the origin of which has been proposed to predate the emergence of eukaryotes. Mimivirus intein exhibits canonical sequence motifs and clearly belongs to a subclass of archaeal inteins always found in the same location of PolB genes. On the other hand, the Mimivirus PolB is most similar to eukaryotic Poldelta sequences.


CONCLUSIONS
The intriguing association of an extremophilic archaeal-type intein with a mesophilic eukaryotic-like PolB in Mimivirus is consistent with the hypothesis that DNA viruses might have been the central reservoir of inteins throughout the course of evolution.
Ogata
Hiroyuki
H
Information Génomique et Structurale, UPR2589 CNRS, IBSM, IFR88, 31 chemin Joseph Aiguier, 13402 Marseille Cedex 20, France. Hiroyuki.Ogata@igs.cnrs-mrs.fr
Raoult
Didier
D
Claverie
Jean-Michel
JM
D000595:Amino Acid Sequence; D000656:Amoeba / Q000821:virology; D000818:Animals; D004267:DNA Viruses / Q000378:metabolism*; D004259:DNA-Directed DNA Polymerase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015967:Gene Expression Regulation, Viral; D047668:Inteins / Q000502:physiology*; D008969:Molecular Sequence Data; D010802:Phylogeny; D014764:Viral Proteins / Q000737:chemistry / Q000378:metabolism*
D014764:Viral Proteins; D004259:DNA-Directed DNA Polymerase