DNA Damage Tolerance Pathway Choice Through Uls1 Modulation of Srs2 SUMOylation inSaccharomyces cerevisiae.
DNA damage tolerance and homologous recombination pathways function to bypass replication-blocking lesions and ensure completion of DNA replication. However, inappropriate activation of these pathways may lead to increased mutagenesis or formation of deleterious recombination intermediates, often leading to cell death or cancer formation in higher organisms. Post-translational modifications of PCNA regulate the choice of repair pathways at replication forks. Its monoubiquitination favors translesion synthesis, while polyubiquitination stimulates template switching. Srs2 helicase binds to small ubiquitin-related modifier (SUMO)-modified PCNA to suppress a subset of Rad51-dependent homologous recombination. Conversely, SUMOylation of Srs2 attenuates its interaction with PCNA Sgs1 helicase and Mus81 endonuclease are crucial for disentanglement of repair intermediates at the replication fork. Deletion of both genes is lethal and can be rescued by inactivation of Rad51-dependent homologous recombination. Here we show thatSaccharomyces cerevisiaeUls1, a member of the Swi2/Snf2 family of ATPases and a SUMO-targeted ubiquitin ligase, physically interacts with both PCNA and Srs2, and promotes Srs2 binding to PCNA by downregulating Srs2-SUMO levels at replication forks. We also identify deletion ofULS1as a suppressor ofmus81Δsgs1Δ synthetic lethality and hypothesize thatuls1Δ mutation results in a partial inactivation of the homologous recombination pathway, detrimental in cells devoid of both Sgs1 and Mus81 We thus propose that Uls1 contributes to the pathway where intermediates generated at replication forks are dismantled by Srs2 bound to SUMO-PCNA. UponULS1deletion, accumulating Srs2-SUMO-unable to bind PCNA-takes part in an alternative PCNA-independent recombination repair salvage pathway(s).
Institute of Experimental Biology, Faculty of Biological Sciences, University of Wrocław, 50-383, Poland.
Karol
K
Kramarz
Institute of Experimental Biology, Faculty of Biological Sciences, University of Wrocław, 50-383, Poland.
Seweryn
S
Mucha
Institute of Experimental Biology, Faculty of Biological Sciences, University of Wrocław, 50-383, Poland.
Ireneusz
I
Litwin
Faculty of Biotechnology, University of Wrocław, 50-383, Poland.
Anna
A
Barg-Wojas
Institute of Experimental Biology, Faculty of Biological Sciences, University of Wrocław, 50-383, Poland.
Robert
R
Wysocki
Faculty of Biotechnology, University of Wrocław, 50-383, Poland dorota.dziadkowiec@uni.wroc.pl.
Dorota
0000-0003-0912-2111
D
Dziadkowiec
D000251:Adenosine Triphosphatases / Q000235:genetics; D004249:DNA Damage / Q000235:genetics*; D004265:DNA Helicases / Q000235:genetics*; D004260:DNA Repair / Q000235:genetics; D004261:DNA Replication / Q000235:genetics; D059765:Homologous Recombination / Q000235:genetics; D011499:Protein Processing, Post-Translational; D011995:Recombination, Genetic; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics*; D015398:Signal Transduction; D058207:Sumoylation / Q000235:genetics
D029701:Saccharomyces cerevisiae Proteins; C061376:SRS2 protein, S cerevisiae; D000251:Adenosine Triphosphatases; C506745:ULS1 protein, S cerevisiae; D004265:DNA Helicases
DNA damage tolerance; PCNA; SUMO; Srs2; replication stress