title: The roles of PCNA SUMOylation, Mms2-Ubc13 and Rad5 in translesion DNA synthesis in Saccharomyces cerevisiae.
abstract: Mms2, in concert with Ubc13 and Rad5, is responsible for polyubiquitination of replication processivity factor PCNA. This modification activates recombination-like DNA damage-avoidance mechanisms, which function in an error-free manner. Cells deprived of Mms2, Ubc13 or Rad5 exhibit mutator phenotypes as a result of the channelling of premutational DNA lesions to often error-prone translesion DNA synthesis (TLS). Here we show that Siz1-mediated PCNA SUMOylation is required for the stimulation of this TLS, despite the presence of PCNA monoubiquitination. The stimulation of spontaneous mutagenesis by Siz1 in cells carrying rad5 and/or mms2 mutations is connected with the known role of PCNA SUMOylation in the inhibition of Rad52-mediated recombination. However, following UV irradiation, Siz1 is engaged in additional, as yet undefined, mechanisms controlling genetic stability at the replication fork. We also demonstrate that in the absence of PCNA SUMOylation, Mms2-Ubc13 and Rad5 may, independently of each other, function in the stimulation of TLS. Based on this finding and on an analysis of the epistatic relationships between SIZ1, MMS2 and RAD5, with respect to UV sensitivity, we conclude that PCNA SUMOylation is responsible for the functional differences between the Mms2 and Rad5 homologues of Saccharomyces cerevisiae and Schizosaccharomyces pombe.
authors.affiliation: Institute of Biochemistry and Biophysics Polish Academy of Sciences, 02-106 Warsaw, Poland.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Halas
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Podlaska
authors.forename: Joanna
authors.initials: J
authors.lastname: Derkacz
authors.forename: Justyna
authors.initials: J
authors.lastname: McIntyre
authors.forename: Adrianna
authors.initials: A
authors.lastname: Skoneczna
authors.forename: Ewa
authors.initials: E
authors.lastname: Sledziewska-Gojska
mesh_terms: D004265:DNA Helicases / Q000378:metabolism*; D004271:DNA, Fungal / Q000096:biosynthesis*; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D058207:Sumoylation; D044763:Ubiquitin-Conjugating Enzymes / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*
chemical_list: D004271:DNA, Fungal; C112520:MMS2 protein, S cerevisiae; D018809:Proliferating Cell Nuclear Antigen; D029701:Saccharomyces cerevisiae Proteins; C471610:UBC13 protein, S cerevisiae; D044763:Ubiquitin-Conjugating Enzymes; D044767:Ubiquitin-Protein Ligases; C076225:RAD5 protein, S cerevisiae; D004265:DNA Helicases; C436837:Siz1 protein, S cerevisiae