Nucleic Acids Research Advance Access originally published online on September 17, 2009
Nucleic Acids Research 2009 37(20):6831-6848; doi:10.1093/nar/gkp742
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Nucleic Acids Research, 2009, Vol. 37, No. 20 6831-6848
© The Author(s) 2009. Published by Oxford University Press.
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.5/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Molecular Biology |
DNA translocation activity of the multifunctional replication protein ORF904 from the archaeal plasmid pRN1
1Department of Biochemistry, 2Department of Macromolecular Chemistry II, University of Bayreuth, Universitätsstrasse 30, 95447 Bayreuth, 3Max-Planck-Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Goettingen and 4University of Applied Research of Northwestern Switzerland, Gründenstrasse 40, 4132 Muttenz, Switzerland
*To whom correspondence should be addressed. Tel: +41 61 4674301; Fax: +41 61 4674701; Email: georg.lipps{at}fhnw.ch
Received April 30, 2009. Revised August 24, 2009. Accepted August 24, 2009.
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.