Elg1, an alternative subunit of the RFC clamp loader, preferentially interacts with SUMOylated PCNA.
Replication-factor C (RFC) is a protein complex that loads the processivity clamp PCNA onto DNA. Elg1 is a conserved protein with homology to the largest subunit of RFC, but its function remained enigmatic. Here, we show that yeast Elg1 interacts physically and genetically with PCNA, in a manner that depends on PCNA modification, and exhibits preferential affinity for SUMOylated PCNA. This interaction is mediated by three small ubiquitin-like modifier (SUMO)-interacting motifs and a PCNA-interacting protein box close to the N-terminus of Elg1. These motifs are important for the ability of Elg1 to maintain genomic stability. SUMOylated PCNA is known to recruit the helicase Srs2, and in the absence of Elg1, Srs2 and SUMOylated PCNA accumulate on chromatin. Strains carrying mutations in both ELG1 and SRS2 exhibit a synthetic fitness defect that depends on PCNA modification. Our results underscore the importance of Elg1, Srs2 and SUMOylated PCNA in the maintenance of genomic stability.
Parnas
Oren
O
Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Ramat Aviv, Israel.
Zipin-Roitman
Adi
A
Pfander
Boris
B
Liefshitz
Batia
B
Mazor
Yuval
Y
Ben-Aroya
Shay
S
Jentsch
Stefan
S
Kupiec
Martin
M
D000595:Amino Acid Sequence; D034961:Antigens, Nuclear / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D004265:DNA Helicases / Q000235:genetics / Q000378:metabolism; D017353:Gene Deletion; D042822:Genomic Instability; D008969:Molecular Sequence Data; D018809:Proliferating Cell Nuclear Antigen; D011485:Protein Binding; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D025841:Small Ubiquitin-Related Modifier Proteins / Q000737:chemistry / Q000378:metabolism*; D054875:Ubiquitination
D034961:Antigens, Nuclear; D002352:Carrier Proteins; C477609:Elg1 protein, S cerevisiae; C546594:POL30 protein, S cerevisiae; D018809:Proliferating Cell Nuclear Antigen; D029701:Saccharomyces cerevisiae Proteins; D025841:Small Ubiquitin-Related Modifier Proteins; C061376:SRS2 protein, S cerevisiae; D004265:DNA Helicases