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Two distinct pathways for completion of base excision repair (BER) have been discovered in eukaryotes: the DNA polymerase beta (Pol beta)-dependent short-patch pathway that involves the replacement of a single nucleotide and the long-patch pathway that entails the resynthesis of 2-6 nucleotides and requires PCNA. We have used cell extracts from Pol beta-deleted mouse fibroblasts to separate subfractions containing either Pol delta or Pol epsilon. These fractions were then tested for their ability to perform both short- and long-patch BER in an in vitro repair assay, using a circular DNA template, containing a single abasic site at a defined position. Remarkably, both Pol delta and Pol epsilon were able to replace a single nucleotide at the lesion site, but the repair reaction is delayed compared to single nucleotide replacement by Pol beta. Furthermore, our observations indicated, that either Pol delta and/or Pol epsilon participate in the long-patch BER. PCNA and RF-C, but not RP-A are required for this process. Our data show for the first time that Pol delta and/or Pol epsilon are directly involved in the long-patch BER of abasic sites and might function as back-up system for Pol beta in one-gap filling reactions.
|Item Type:||Journal Article, refereed|
|Communities & Collections:||05 Vetsuisse Faculty > Institute of Veterinary Biochemistry and Molecular Biology|
|DDC:||570 Life sciences; biology|
|Date:||29 August 1998|
|Deposited On:||11 Feb 2008 13:18|
|Last Modified:||27 Nov 2013 22:36|
|Publisher:||Nature Publishing Group|
|Citations:||Web of Science®. Times cited: 132|
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