title: Elg1, the major subunit of an alternative RFC complex, interacts with SUMO-processing proteins.
abstract: PCNA is a homotrimeric ring with important roles in DNA replication and repair. PCNA is loaded and unloaded by the RFC complex, which is composed of five subunits (Rfc1-5). Three additional complexes that share with RFC the small subunits (Rfc2-5) and contain alternative large subunits were found in yeast and other eukaryotes. We have recently reported that one of these, the Elg1-RFC complex, interacts with SUMOylated PCNA and may play a role in its unloading during DNA repair. Here we report that a yeast-two-hybrid screen with the N terminus of Elg1(which interacts with SUMOylated PCNA) uncovered interactions with proteins that belong to the SUMO pathway, including Slx5 and Slx8, which form an E3 ubiquitin ligase that ubiquitinates SUMOylated proteins. Mutations in SLX5 result in a genomic instability phenotype similar to that of elg1 mutants. The physical interaction between the N terminus of Elg1 and Slx5 is mediated by poly-SUMO chains but not by PCNA modifications, and requires Siz2, but not Siz1, activity. Thus our results highlight the many important roles played by Elg1, some of which are PCNA-dependent and some PCNA-independent.
authors.affiliation: Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Ramat Aviv, Israel.
authors.forename: Oren
authors.initials: O
authors.lastname: Parnas
authors.forename: Rona
authors.initials: R
authors.lastname: Amishay
authors.forename: Batia
authors.initials: B
authors.lastname: Liefshitz
authors.forename: Adi
authors.initials: A
authors.lastname: Zipin-Roitman
authors.forename: Martin
authors.initials: M
authors.lastname: Kupiec
mesh_terms: D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D004260:DNA Repair; D017353:Gene Deletion; D005800:Genes, Fungal; D042822:Genomic Instability; D059765:Homologous Recombination; D009154:Mutation; D010641:Phenotype; D010957:Plasmids / Q000235:genetics / Q000378:metabolism; D018809:Proliferating Cell Nuclear Antigen / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D025841:Small Ubiquitin-Related Modifier Proteins / Q000235:genetics / Q000378:metabolism; D020798:Two-Hybrid System Techniques; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism; D054875:Ubiquitination
chemical_list: D002352:Carrier Proteins; C477609:Elg1 protein, S cerevisiae; D018809:Proliferating Cell Nuclear Antigen; D029701:Saccharomyces cerevisiae Proteins; C436836:Siz2 protein, S cerevisiae; D025841:Small Ubiquitin-Related Modifier Proteins; C515574:Slx8 protein, S cerevisiae; D044767:Ubiquitin-Protein Ligases; C515573:Slx5 protein, S cerevisiae