Nucleic Acids Research Advance Access originally published online on September 28, 2007
Nucleic Acids Research 2007 35(19):6588-6597; doi:10.1093/nar/gkm741
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Nucleic Acids Research, 2007, Vol. 35, No. 19 6588-6597
© 2007 The Author(s)
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Nucleic Acid Enzymes |
The eukaryotic leading and lagging strand DNA polymerases are loaded onto primer-ends via separate mechanisms but have comparable processivity in the presence of PCNA
1Department of Medical Biochemistry and Biophysics, 2Department of Biochemistry, Umeå University, 901 87 Umeå, Sweden and 3Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St Louis, MO 63110, USA
*To whom correspondence should be addressed. Tel: +46 90 786 6638; Fax: +46 90 786 9795; Email: erik.johansson{at}medchem.umu.se
Received June 9, 2007. Revised September 6, 2007. Accepted September 6, 2007.
Saccharomyces cerevisiae DNA polymerase
(Pol
) and DNA polymerase
(Pol
) are replicative DNA polymerases at the replication fork. Both enzymes are stimulated by PCNA, although to different levels. To understand why and to explore the interaction with PCNA, we compared Pol
and Pol
in physical interactions with PCNA and nucleic acids (with or without RPA), and in functional assays measuring activity and processivity. Using surface plasmon resonance technique, we show that Pol
has a high affinity for DNA, but a low affinity for PCNA. In contrast, Pol
has a low affinity for DNA and a high affinity for PCNA. The true processivity of Pol
and Pol
was measured for the first time in the presence of RPA, PCNA and RFC on single-stranded DNA. Remarkably, in the presence of PCNA, the processivity of Pol
and Pol
on RPA-coated DNA is comparable. Finally, more PCNA molecules were found on the template after it was replicated by Pol
when compared to Pol
. We conclude that Pol
and Pol
exhibit comparable processivity, but are loaded on the primer-end via different mechanisms.
Present address: Peter Stenlund, Biopharmaceuticals Octapharma AB, 11275 Stockholm, Sweden
Pawel Grabowski, Department of Medical Biosciences, Umeå University, 901 87 Umeå, Sweden