A SUMO-Like Domain Protein, Esc2, Is Required for Genome Integrity and Sister Chromatid Cohesion in Saccharomyces cerevisiae

Abstract

The ESC2 gene encodes a protein with two tandem C-terminal SUMO-like domains and is conserved from yeasts to humans. Previous studies have implicated Esc2 in gene silencing. Here, we explore the functional significance of SUMO-like domains and describe a novel role for Esc2 in promoting genome integrity during DNA replication. This study shows that esc2D cells are modestly sensitive to hydroxyurea (HU) and defective in sister chromatid cohesion and have a reduced life span, and these effects are enhanced by deletion of the RRM3 gene that is a Pif1-like DNA helicase. esc2D rrm3D cells also have a severe growth defect and accumulate DNA damage in late S/G 2 . In contrast, esc2D does not enhance the HU sensitivity or sister chromatid cohesion defect in mrc1D cells, but rather partially suppresses both phenotypes. We also show that deletion of both Esc2 SUMO-like domains destabilizes Esc2 protein and functionally inactivates Esc2, but this phenotype is suppressed by an Esc2 variant with an authentic SUMO domain. These results suggest that Esc2 is functionally equivalent to a stable SUMO fusion protein and plays important roles in facilitating DNA replication fork progression and sister chromatid cohesion that would otherwise impede the replication fork in rrm3D cells.

Distinct SUMO Ligases Cooperate with Esc2 and Slx5 to Suppress Duplication-Mediated Genome Rearrangements

“…ESC2 encodes a protein containing two SUMO-like domains [6]–[8] and plays a role in sister chromatid cohesion in conjunction with Smc5-Smc6 in the repair of damage during DNA replication [39], [40]. Deletion of ESC2 also causes a strong defect in suppressing GCRs, particularly duplication-mediated GCRs, though less than that caused by the mms21-11 allele (Table 1) [5].…”

“…Both MMS21 and ESC2 suppress duplication-mediated GCRs (Table 1), are epistatic with each other (Table 1), and prevent the formation of X-shaped DNA replication intermediates [7], [39], [40]. Esc2 contains SUMO-like domains and no known enzymatic activity [6], but physically interacts with components of the SUMO pathway, including Ubc9 and Smt3 itself [7]. Previous studies of Rad60, an ortholog of Esc2 in fission yeast, identified an interaction between Rad60 and the Smc5-Smc6 complex and showed that Rad60 functions in the same pathway as Nse2, the fission ortholog of Mms21 [59], [60].…”

“…The yeast Saccharomyces cerevisiae provides a powerful model system to study genome rearrangements [4], and many genes in S. cerevisiae have been found to suppress gross chromosomal rearrangements (GCRs), including those mediated by single-copy sequences and those mediated by segmental duplications [5]. Interestingly, a number of these genes are involved in protein sumoylation [5]: Esc2 contains tandem SUMO-like domains [6]–[8], and Slx5 is a subunit of the Slx5-Slx8 complex, which was shown to be a SUMO-targeted ubiquitin ligase [9],[10]. In contrast, Siz1, a SUMO E3 ligase [11], does not have a significant role in suppressing duplication-mediated GCRs [12].…”

Schizosaccharomyces pombe Cds1Chk2 regulates homologous recombination at stalled replication forks through the phosphorylation of recombination protein Rad60

“…It has also been reported that Smc5/6 accumulates at the sites of DNA double-strand breaks or collapsed replication forks (Lindroos et al, 2006). S. cerevisiae ESC2 is a putative homolog of rad60, and has been shown to be involved in chromatin silencing and sister chromatid cohesion (Dhillon and Kamakaka, 2000;Ohya et al, 2008). However, there is no evidence that S. pombe Smc5/6 has similar activity, and a correlative interaction between ESC2p and Smc5/6 has not been reported.…”

Loss of F-box Motif Encoding Gene SAF1 and RRM3 Together Leads to Synthetic Growth Defect and Sensitivity to HU, MMS inS.cerevisiae

“…The hydroxyurea (HU) and methyl methanesulfonate (MMS) act as replication checkpoint inhibitor and DNA damaging agent respectively. The Rrm3 mutant reported to have slightly sensitive phenotype in the 200mM hydroxyurea (22). With regard to SAF1 mutant the data is not available.…”