The dCMP transferase activity of yeast Rev1 is biologically relevant during the bypass of endogenously generated AP sites.
The bypass of AP sites in yeast requires the Rev1 protein in addition to the Pol ζ translesion synthesis DNA polymerase. Although Rev1 was originally characterized biochemically as a dCMP transferase during AP-site bypass, the relevance of this activity in vivo is unclear. The current study uses highly sensitive frameshift- and nonsense-reversion assays to monitor the bypass of AP sites created when uracil is excised from chromosomal DNA. In the frameshift-reversion assay, an unselected base substitution frequently accompanies the selected mutation, allowing the relative incorporation of each of the four dNMPs opposite endogenously created AP sites to be inferred. Results with this assay suggest that dCMP is the most frequent dNMP inserted opposite uracil-derived AP sites and demonstrate that dCMP insertion absolutely requires the catalytic activity of Rev1. In the complementary nonsense-reversion assay, dCMP insertion likewise depended on the dCMP transferase activity of Rev1. Because dAMP insertion opposite uracil-derived AP sites does not revert the nonsense allele and hence could not be detected, it also was possible to detect low levels of dGMP or dTMP insertion upon loss of Rev1 catalytic activity. These results demonstrate that the catalytic activity of Rev1 is biologically relevant and is required specifically for dCMP insertion during the bypass of endogenous AP sites.
Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, United States.
Nayun
N
Kim
Sarah V
SV
Mudrak
Sue
S
Jinks-Robertson
D000483:Alleles; D001483:Base Sequence; D055162:Biocatalysis; D004249:DNA Damage; D004271:DNA, Fungal / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism; D003843:Deoxycytidine Monophosphate / Q000378:metabolism*; D008969:Molecular Sequence Data; D009713:Nucleotidyltransferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017384:Sequence Deletion; D000099270:Y-Family DNA Polymerases
D004271:DNA, Fungal; D004259:DNA-Directed DNA Polymerase; D003843:Deoxycytidine Monophosphate; D009713:Nucleotidyltransferases; D029701:Saccharomyces cerevisiae Proteins; C425929:DNA polymerase zeta; C100951:REV1 protein, S cerevisiae; D000099270:Y-Family DNA Polymerases; C112338:Rad30 protein