title: The Functions of Serine 687 Phosphorylation of Human DNA Polymerase η in UV Damage Tolerance.
abstract: DNA polymerase η (polη) is a Y-family translesion synthesis polymerase that plays a key role in the cellular tolerance toward UV irradiation-induced DNA damage. Here, we identified, for the first time, the phosphorylation of serine 687 (Ser(687)), which is located in the highly conserved nuclear localization signal (NLS) region of human polη and is mediated by cyclin-dependent kinase 2 (CDK2). We also showed that this phosphorylation is stimulated in human cells upon UV light exposure and results in diminished interaction of polη with proliferating cell nuclear antigen (PCNA). Furthermore, we demonstrated that the phosphorylation of Ser(687) in polη confers cellular protection from UV irradiation and increases the efficiency in replication across a site-specifically incorporated cyclobutane pyrimidine dimer in human cells. Based on these results, we proposed a mechanistic model where Ser(687) phosphorylation functions in the reverse polymerase switching step of translesion synthesis: The phosphorylation brings negative charges to the NLS of polη, which facilitates its departure from PCNA, thereby resetting the replication fork for highly accurate and processive DNA replication. Thus, our study, together with previous findings, supported that the posttranslational modifications of NLS of polη played a dual role in polymerase switching, where Lys(682) deubiquitination promotes the recruitment of polη to PCNA immediately prior to lesion bypass and Ser(687) phosphorylation stimulates its departure from the replication fork immediately after lesion bypass.
authors.affiliation: From the §Department of Chemistry, University of California, Riverside, California 92521-0403.
authors.forename: Xiaoxia
authors.initials: X
authors.lastname: Dai
authors.affiliation: From the §Department of Chemistry, University of California, Riverside, California 92521-0403.
authors.forename: Changjun
authors.initials: C
authors.lastname: You
authors.affiliation: From the §Department of Chemistry, University of California, Riverside, California 92521-0403 Yinsheng.Wang@ucr.edu.
authors.forename: Yinsheng
authors.initials: Y
authors.lastname: Wang
mesh_terms: D002460:Cell Line; D051357:Cyclin-Dependent Kinase 2 / Q000378:metabolism; D004247:DNA / Q000737:chemistry* / Q000528:radiation effects; D004249:DNA Damage; D004261:DNA Replication; D004259:DNA-Directed DNA Polymerase / Q000737:chemistry* / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D013058:Mass Spectrometry; D019913:Nuclear Localization Signals / Q000737:chemistry*; D010766:Phosphorylation; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D011740:Pyrimidine Dimers / Q000378:metabolism*; D012694:Serine / Q000378:metabolism*; D014466:Ultraviolet Rays; D000099270:Y-Family DNA Polymerases
chemical_list: D051357:Cyclin-Dependent Kinase 2; D004247:DNA; D004259:DNA-Directed DNA Polymerase; D019913:Nuclear Localization Signals; D018809:Proliferating Cell Nuclear Antigen; D011740:Pyrimidine Dimers; D012694:Serine; C495894:CDK2 protein, human; C112338:Rad30 protein; D000099270:Y-Family DNA Polymerases