title: DNA translocation activity of the multifunctional replication protein ORF904 from the archaeal plasmid pRN1.
abstract: The replication protein ORF904 from the plasmid pRN1 is a multifunctional enzyme with ATPase-, primase- and DNA polymerase activity. Sequence analysis suggests the presence of at least two conserved domains: an N-terminal prim/pol domain with primase and DNA polymerase activities and a C-terminal superfamily 3 helicase domain with a strong double-stranded DNA dependant ATPase activity. The exact molecular function of the helicase domain in the process of plasmid replication remains unclear. Potentially this motor protein is involved in duplex remodelling and/or origin opening at the plasmid replication origin. In support of this we found that the monomeric replication protein ORF904 forms a hexameric ring in the presence of DNA. It is able to translocate along single-stranded DNA in 3'-5' direction as well as on double-stranded DNA. Critical residues important for ATPase activity and DNA translocation activity were identified and are in agreement with a homology model of the helicase domain. In addition we propose that a winged helix DNA-binding domain at the C-terminus of the helicase domain could assist the binding of the replication protein specifically to the replication origin.
authors.affiliation: Department of Biochemistry, University of Bayreuth, Universitätsstrasse 30, 95447 Bayreuth, Switzerland.
authors.forename: Martin
authors.initials: M
authors.lastname: Sanchez
authors.forename: Markus
authors.initials: M
authors.lastname: Drechsler
authors.forename: Holger
authors.initials: H
authors.lastname: Stark
authors.forename: Georg
authors.initials: G
authors.lastname: Lipps
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D019843:Archaeal Proteins / Q000378:metabolism*; D004247:DNA / Q000378:metabolism*; D004265:DNA Helicases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D008958:Models, Molecular; D010957:Plasmids / Q000378:metabolism; D017354:Point Mutation; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary
chemical_list: D019843:Archaeal Proteins; D004268:DNA-Binding Proteins; D004247:DNA; D000251:Adenosine Triphosphatases; D004265:DNA Helicases