Molecular and Cellular Biology, November 2007, p. 7758-7764, Vol. 27, No. 21
0270-7306/07/$08.00+0 doi:10.1128/MCB.01331-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, 301 University Blvd., Galveston, Texas 77555-1061
Received 24 July 2007/ Returned for modification 12 August 2007/ Accepted 23 August 2007
In Saccharomyces cerevisiae, replication through DNA lesions is promoted by Rad6-Rad18-dependent processes that include translesion synthesis by DNA polymerases
and
and a Rad5-Mms2-Ubc13-controlled postreplicational repair (PRR) pathway which repairs the discontinuities in the newly synthesized DNA that form opposite from DNA lesions on the template strand. Here, we examine the contributions of the RAD51, RAD52, and RAD54 genes and of the RAD50 and XRS2 genes to the PRR of UV-damaged DNA. We find that deletions of the RAD51, RAD52, and RAD54 genes impair the efficiency of PRR and that almost all of the PRR is inhibited in the absence of both Rad5 and Rad52. We suggest a role for the Rad5 pathway when the lesion is located on the leading strand template and for the Rad52 pathway when the lesion is located on the lagging strand template. We surmise that both of these pathways operate in a nonrecombinational manner, Rad5 by mediating replication fork regression and template switching via its DNA helicase activity and Rad52 via a synthesis-dependent strand annealing mode. In addition, our results suggest a role for the Rad50 and Xrs2 proteins and thereby for the MRX complex in promoting PRR via both the Rad5 and Rad52 pathways.
Published ahead of print on 4 September 2007.
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