title: RAD18-independent ubiquitination of proliferating-cell nuclear antigen in the avian cell line DT40.
abstract: Ubiquitination of proliferating-cell nuclear antigen (PCNA) at K164 by RAD6/RAD18 has a key role in DNA damage tolerance in yeast. Here, we report on the first genetic study of this modification in a vertebrate cell. As in yeast, mutation of K164 of PCNA to arginine in the avian cell line DT40 results in sensitivity to DNA damage but, by contrast, the DT40 pcnaK164R mutant is more sensitive than the rad18 mutant. Consistent with this, we show the presence of residual ubiquitination of PCNA at K164 in the absence of functional RAD18, suggesting the presence of an alternate PCNA ubiquitinating enzyme in DT40. Furthermore, RAD18 and PCNA K164 have non-overlapping roles in the suppression of sister chromatid exchange in DT40, showing that RAD18 has other functions that do not involve the ubiquitination of PCNA.
authors.affiliation: Medical Research Council Laboratory of Molecular Biology, Division of Protein & Nucleic Acid Chemistry, Hills Road, Cambridge CB2 2QH, UK.
authors.forename: Laura J
authors.initials: LJ
authors.lastname: Simpson
authors.forename: Anna-Laura
authors.initials: AL
authors.lastname: Ross
authors.forename: Dávid
authors.initials: D
authors.lastname: Szüts
authors.forename: Cherry A
authors.initials: CA
authors.lastname: Alviani
authors.forename: Vibe H
authors.initials: VH
authors.lastname: Oestergaard
authors.forename: Ketan J
authors.initials: KJ
authors.lastname: Patel
authors.forename: Julian E
authors.initials: JE
authors.lastname: Sale
mesh_terms: D000818:Animals; D002460:Cell Line; D049109:Cell Proliferation; D002645:Chickens; D004249:DNA Damage; D004261:DNA Replication; D009154:Mutation; D018809:Proliferating Cell Nuclear Antigen / Q000235:genetics* / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D012854:Sister Chromatid Exchange; D014162:Transfection; D025801:Ubiquitin / Q000378:metabolism*
chemical_list: D018809:Proliferating Cell Nuclear Antigen; D025801:Ubiquitin