The Saccharomyces cerevisiae Rad6 postreplication repair and Siz1/Srs2 homologous recombination-inhibiting pathways process DNA damage that arises in asf1 mutants.
The Asf1 and Rad6 pathways have been implicated in a number of common processes such as suppression of gross chromosomal rearrangements (GCRs), DNA repair, modification of chromatin, and proper checkpoint functions. We examined the relationship between Asf1 and different gene products implicated in postreplication repair (PRR) pathways in the suppression of GCRs, checkpoint function, sensitivity to hydroxyurea (HU) and methyl methanesulfonate (MMS), and ubiquitination of proliferating cell nuclear antigen (PCNA). We found that defects in Rad6 PRR pathway and Siz1/Srs2 homologous recombination suppression (HRS) pathway genes suppressed the increased GCR rates seen in asf1 mutants, which was independent of translesion bypass polymerases but showed an increased dependency on Dun1. Combining an asf1 deletion with different PRR mutations resulted in a synergistic increase in sensitivity to chronic HU and MMS treatment; however, these double mutants were not checkpoint defective, since they were capable of recovering from acute treatment with HU. Interestingly, we found that Asf1 and Rad6 cooperate in ubiquitination of PCNA, indicating that Rad6 and Asf1 function in parallel pathways that ubiquitinate PCNA. Our results show that ASF1 probably contributes to the maintenance of genome stability through multiple mechanisms, some of which involve the PRR and HRS pathways.
Kats
Ellen S
ES
Ludwig Institute for Cancer Research, Departments of Medicine and Cellular and Molecular Medicine, and Biomedical Sciences Graduate Program, UC San Diego School of Medicine, 9500 Gilman Drive, La Jolla, CA 92093-0669, USA.
Enserink
Jorrit M
JM
Martinez
Sandra
S
Kolodner
Richard D
RD
D018797:Cell Cycle Proteins / Q000235:genetics* / Q000378:metabolism; D015825:Chromosomes, Fungal; D004249:DNA Damage; D004265:DNA Helicases / Q000235:genetics* / Q000378:metabolism; D004260:DNA Repair; D004261:DNA Replication; D004271:DNA, Fungal / Q000235:genetics / Q000378:metabolism; D006918:Hydroxyurea / Q000494:pharmacology; D008741:Methyl Methanesulfonate / Q000494:pharmacology; D018832:Molecular Chaperones / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D011995:Recombination, Genetic; D016196:S Phase; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism; D044763:Ubiquitin-Conjugating Enzymes / Q000235:genetics* / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000235:genetics* / Q000378:metabolism; D054875:Ubiquitination
C109731:ASF1 protein, S cerevisiae; D018797:Cell Cycle Proteins; D004271:DNA, Fungal; D018832:Molecular Chaperones; D029701:Saccharomyces cerevisiae Proteins; C061376:SRS2 protein, S cerevisiae; D008741:Methyl Methanesulfonate; C471606:RAD6 protein, S cerevisiae; D044763:Ubiquitin-Conjugating Enzymes; D044767:Ubiquitin-Protein Ligases; C104169:DUN1 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases; D004265:DNA Helicases; C436837:Siz1 protein, S cerevisiae; D006918:Hydroxyurea