title: SUMO-modified PCNA recruits Srs2 to prevent recombination during S phase.
abstract: Damaged DNA, if not repaired before replication, can lead to replication fork stalling and genomic instability; however, cells can switch to different damage bypass modes that permit replication across lesions. Two main bypasses are controlled by ubiquitin modification of proliferating cell nuclear antigen (PCNA), a homotrimeric DNA-encircling protein that functions as a polymerase processivity factor and regulator of replication-linked functions. Upon DNA damage, PCNA is modified at the conserved lysine residue 164 by either mono-ubiquitin or a lysine-63-linked multi-ubiquitin chain, which induce error-prone or error-free replication bypasses of the lesions. In S phase, even in the absence of exogenous DNA damage, yeast PCNA can be alternatively modified by the small ubiquitin-related modifier protein SUMO; however the consequences of this remain controversial. Here we show by genetic analysis that SUMO-modified PCNA functionally cooperates with Srs2, a helicase that blocks recombinational repair by disrupting Rad51 nucleoprotein filaments. Moreover, Srs2 displays a preference for interacting directly with the SUMO-modified form of PCNA, owing to a specific binding site in its carboxy-terminal tail. Our finding suggests a model in which SUMO-modified PCNA recruits Srs2 in S phase in order to prevent unwanted recombination events of replicating chromosomes.
authors.affiliation: Department of Molecular Cell Biology, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany.
authors.forename: Boris
authors.initials: B
authors.lastname: Pfander
authors.forename: George-Lucian
authors.initials: GL
authors.lastname: Moldovan
authors.forename: Meik
authors.initials: M
authors.lastname: Sacher
authors.forename: Carsten
authors.initials: C
authors.lastname: Hoege
authors.forename: Stefan
authors.initials: S
authors.lastname: Jentsch
mesh_terms: D015825:Chromosomes, Fungal / Q000235:genetics / Q000378:metabolism; D004249:DNA Damage; D004265:DNA Helicases / Q000737:chemistry / Q000378:metabolism*; D004261:DNA Replication; D004843:Epistasis, Genetic; D016296:Mutagenesis / Q000235:genetics; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D018809:Proliferating Cell Nuclear Antigen / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D011995:Recombination, Genetic / Q000235:genetics; D016196:S Phase; D025842:SUMO-1 Protein / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012689:Sequence Homology, Nucleic Acid; D013379:Substrate Specificity; D044763:Ubiquitin-Conjugating Enzymes / Q000235:genetics / Q000378:metabolism
chemical_list: D018809:Proliferating Cell Nuclear Antigen; D025842:SUMO-1 Protein; D029701:Saccharomyces cerevisiae Proteins; C061376:SRS2 protein, S cerevisiae; C471606:RAD6 protein, S cerevisiae; D044763:Ubiquitin-Conjugating Enzymes; D004265:DNA Helicases