Novel RepA-MCM proteins encoded in plasmids pTAU4, pORA1 and pTIK4 from Sulfolobus neozealandicus
Bo Greve (1), Susanne Jensen (1), Hoa Phan (1), Kim Brügger (1), Wolfram Zillig (2), Qunxin She (1) and Roger A. Garrett (1,3)
1. Danish Archaea Centre, Institute of Molecular Biology, University of Copenhagen, Sølvgade 83H, DK-1307 Copenhagen, Denmark / 2. Max-Planck-Institut für Biochemie, D-82152 Martinsried, Germany / 3. Corresponding author ([email protected]) / Received September 2, 2004; accepted November 8, 2004; published online November 29, 2004
Three plasmids isolated from the crenarchaeal thermoacidophile Sulfolobus neozealandicus were characterized. Plasmids pTAU4 (7,192 bp), pORA1 (9,689 bp) and pTIK4 (13,638 bp) show unusual properties that distinguish them from previously characterized cryptic plasmids of the genus Sulfolobus. Plasmids pORA1 and pTIK4 encode RepA proteins, only the former of which carries the novel polymerase–primase domain of other known Sulfolobus plasmids. Plasmid pTAU4 encodes a mini-chromosome maintenance protein homolog and no RepA protein; the implications for DNA replication are considered. Plasmid pORA1 is the first Sulfolobus plasmid to be characterized that does not encode the otherwise highly conserved DNA-binding PlrA protein. Another encoded protein appears to be specific for the New Zealand plasmids. The three plasmids should provide useful model systems for functional studies of these important crenarchaeal proteins.
Keywords: chemotaxis, crenarchaeal plasmid, DNA replicase, MCM protein.