title: Effects of accessory proteins on the bypass of a cis-syn thymine-thymine dimer by Saccharomyces cerevisiae DNA polymerase eta.
abstract: Among several hypotheses to explain how translesion synthesis (TLS) by DNA polymerase eta (pol eta) suppresses ultraviolet light-induced mutagenesis in vivo despite the fact that pol eta copies DNA with low fidelity, here we test whether replication accessory proteins enhance the fidelity of TLS by pol eta. We first show that the single-stranded DNA binding protein RPA, the sliding clamp PCNA, and the clamp loader RFC slightly increase the processivity of yeast pol eta and its ability to recycle to new template primers. However, these increases are small, and they are similar when copying an undamaged template and a template containing a cis-syn TT dimer. Consequently, the accessory proteins do not strongly stimulate the already robust TT dimer bypass efficiency of pol eta. We then perform a comprehensive analysis of yeast pol eta fidelity. We show that it is much less accurate than other yeast DNA polymerases and that the accessory proteins have little effect on fidelity when copying undamaged templates or when bypassing a TT dimer. Thus, although accessory proteins clearly participate in pol eta functions in vivo, they do not appear to help suppress UV mutagenesis by improving pol eta bypass fidelity per se.
authors.affiliation: Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA.
authors.forename: Scott D
authors.initials: SD
authors.lastname: McCulloch
authors.forename: Adam
authors.initials: A
authors.lastname: Wood
authors.forename: Parie
authors.initials: P
authors.lastname: Garg
authors.forename: Peter M J
authors.initials: PM
authors.lastname: Burgers
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Kunkel
mesh_terms: D020029:Base Pairing; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D004249:DNA Damage; D004260:DNA Repair; D004261:DNA Replication; D004271:DNA, Fungal / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004259:DNA-Directed DNA Polymerase / Q000235:genetics / Q000378:metabolism*; D016296:Mutagenesis; D018809:Proliferating Cell Nuclear Antigen / Q000235:genetics / Q000378:metabolism; D011740:Pyrimidine Dimers / Q000235:genetics / Q000378:metabolism*; D051716:Replication Protein A / Q000235:genetics / Q000378:metabolism; D051818:Replication Protein C / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D013698:Templates, Genetic; D014466:Ultraviolet Rays; D000099270:Y-Family DNA Polymerases
chemical_list: D018797:Cell Cycle Proteins; D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D004259:DNA-Directed DNA Polymerase; D018809:Proliferating Cell Nuclear Antigen; D011740:Pyrimidine Dimers; D051716:Replication Protein A; D051818:Replication Protein C; D029701:Saccharomyces cerevisiae Proteins; C084903:RFC1 protein, S cerevisiae; C112338:Rad30 protein; D000099270:Y-Family DNA Polymerases