Sequence of plasmid pGT5 from the archaeon Pyrococcus abyssi: evidence for rolling-circle replication in a hyperthermophile.
The plasmid pGT5 (3,444 bp) from the hyperthermophilic archaeon Pyrococcus abyssi GE5 has been completely sequenced. Two major open reading frames with a good coding probability are located on the same strand and cover 85% of the total sequence. The larger open reading frame encodes a putative polypeptide which exhibits sequence similarity with Rep proteins of plasmids using the rolling-circle mechanism for replication. Upstream of this open reading frame, we have detected an 11-bp motif identical to the double-stranded origin of several bacterial plasmids that replicate via the rolling-circle mechanism. A putative single-stranded origin exhibits similarities both to bacterial primosome-dependent single-stranded initiation sites and to bacterial primase (dnaG) start sites. A single-stranded form of pGT5 corresponding to the plus strand was detected in cells of P. abyssi. These data indicate that pGT5 replicates via the rolling-circle mechanism and suggest that members of the domain Archaea contain homologs of several bacterial proteins involved in chromosomal DNA replication. Phylogenetic analysis of Rep proteins from rolling-circle replicons suggest that diverse families diverged before the separation of the domains Archaea, Bacteria, and Eucarya.
Erauso
G
G
Station Biologique de Roscoff, UPR 9042 Centre National de la Recherche Scientifique, Université Paris-Sud, France.
Marsin
S
S
Benbouzid-Rollet
N
N
Baucher
M F
MF
Barbeyron
T
T
Zivanovic
Y
Y
Prieur
D
D
Forterre
P
P
D000595:Amino Acid Sequence; D001105:Archaea / Q000235:genetics*; D001483:Base Sequence; D004261:DNA Replication; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010802:Phylogeny; D010957:Plasmids