title: DNA damage bypass operates in the S and G2 phases of the cell cycle and exhibits differential mutagenicity.
abstract: Translesion DNA synthesis (TLS) employs low-fidelity DNA polymerases to bypass replication-blocking lesions, and being associated with chromosomal replication was presumed to occur in the S phase of the cell cycle. Using immunostaining with anti-replication protein A antibodies, we show that in UV-irradiated mammalian cells, chromosomal single-stranded gaps formed in S phase during replication persist into the G2 phase of the cell cycle, where their repair is completed depending on DNA polymerase ζ and Rev1. Analysis of TLS using a high-resolution gapped-plasmid assay system in cell populations enriched by centrifugal elutriation for specific cell cycle phases showed that TLS operates both in S and G2. Moreover, the mutagenic specificity of TLS in G2 was different from S, and in some cases overall mutation frequency was higher. These results suggest that TLS repair of single-stranded gaps caused by DNA lesions can lag behind chromosomal replication, is separable from it, and occurs both in the S and G2 phases of the cell cycle. Such a mechanism may function to maintain efficient replication, which can progress despite the presence of DNA lesions, with TLS lagging behind and patching regions of discontinuity.
authors: Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel,
authors: Noam
authors: N
authors: Diamant
authors: Ayal
authors: A
authors: Hendel
authors: Ilan
authors: I
authors: Vered
authors: Thomas
authors: T
authors: Carell
authors: Thomas
authors: T
authors: Reissner
authors: Niels
authors: N
authors: de Wind
authors: Nicholas
authors: N
authors: Geacinov
authors: Zvi
authors: Z
authors: Livneh
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis*; D004249:DNA Damage; D004268:DNA-Binding Proteins / Q000502:physiology; D004259:DNA-Directed DNA Polymerase / Q000502:physiology; D016195:G2 Phase / Q000235:genetics*; D006801:Humans; D051379:Mice; D016296:Mutagenesis; D009687:Nuclear Proteins / Q000502:physiology; D009713:Nucleotidyltransferases / Q000502:physiology; D051716:Replication Protein A / Q000032:analysis; D016196:S Phase / Q000235:genetics*; D014466:Ultraviolet Rays; D000099270:Y-Family DNA Polymerases
chemical_list: D004247:DNA; D004268:DNA-Binding Proteins; D004259:DNA-Directed DNA Polymerase; D009687:Nuclear Proteins; D009713:Nucleotidyltransferases; D051716:Replication Protein A; C429004:REV1 protein, human; D000099270:Y-Family DNA Polymerases; C118285:REV3L protein, human