title: SUMOylation regulates Rad18-mediated template switch.
abstract: Replication by template switch is thought to mediate DNA damage-bypass and fillings of gaps. Gap-filling repair requires homologous recombination as well as Rad18- and Rad5-mediated proliferating cell nuclear antigen (PCNA) polyubiquitylation. However, it is unclear whether these processes are coordinated, and the physical evidence for Rad18-Rad5-dependent template switch at replication forks is still elusive. Here we show, using genetic and physical approaches, that in budding yeast (Saccharomyces cerevisiae) Rad18 is required for the formation of X-shaped sister chromatid junctions (SCJs) at damaged replication forks through a process involving PCNA polyubiquitylation and the ubiquitin-conjugating enzymes Mms2 and Ubc13. The Rad18-Mms2-mediated damage-bypass through SCJs requires the small ubiquitin-like modifier (SUMO)-conjugating enzyme Ubc9 and SUMOylated PCNA, and is coordinated with Rad51-dependent recombination events. We propose that the Rad18-Rad5-Mms2-dependent SCJs represent template switch events. Altogether, our results unmask a role for PCNA ubiquitylation and SUMOylation pathways in promoting transient damage-induced replication-coupled recombination events involving sister chromatids at replication forks.
authors.affiliation: IFOM, the FIRC Institute for Molecular Oncology Foundation, IFOM-IEO Campus, Via Adamello 16, 20139 Milan, Italy. dana.branzei@ifom-ieo-campus.it
authors.forename: Dana
authors.initials: D
authors.lastname: Branzei
authors.forename: Fabio
authors.initials: F
authors.lastname: Vanoli
authors.forename: Marco
authors.initials: M
authors.lastname: Foiani
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D004249:DNA Damage; D004265:DNA Helicases; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000378:metabolism*; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D053484:RecQ Helicases / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D012854:Sister Chromatid Exchange; D025841:Small Ubiquitin-Related Modifier Proteins / Q000378:metabolism*; D013698:Templates, Genetic; D044763:Ubiquitin-Conjugating Enzymes / Q000235:genetics / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases; D054875:Ubiquitination
chemical_list: D004268:DNA-Binding Proteins; C112520:MMS2 protein, S cerevisiae; D018809:Proliferating Cell Nuclear Antigen; C063607:RAD18 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D025841:Small Ubiquitin-Related Modifier Proteins; C471610:UBC13 protein, S cerevisiae; D044763:Ubiquitin-Conjugating Enzymes; D044767:Ubiquitin-Protein Ligases; D000251:Adenosine Triphosphatases; C076225:RAD5 protein, S cerevisiae; C090472:SGS1 protein, S cerevisiae; D004265:DNA Helicases; D053484:RecQ Helicases