S. pombeDNA translocases Rrp1 and Rrp2 have distinct roles at centromeres and telomeres that ensure genome stability

Abstract

STATEMENTSchizosaccharomyces pombe DNA translocases Rrp1 and Rrp2 modulate centromere and telomere maintenance pathways and dysregulation of their activity leads to genome instability. ABSTRACTHomologous recombination (HR) is a DNA repair mechanism that ensures, together with heterochromatin machinery, the proper replication, structure and function of telomeres and centromeres that is essential for the maintenance of genome integrity. Schizosaccharomyces pombe Rrp1 and Rrp2 participate in HR and are orthologues of Saccharomyces cerevisiae Uls1, a SWI2/SNF2 DNA translocase and SUMO-Targeted Ubiquitin Ligase. We show that Rrp1 or Rrp2 upregulation leads to chromosome instability and growth defects. These phenotypes depend on putative DNA translocase activities of Rrp1 and Rrp2. Either Rrp1 or Rrp2 overproduction results in a reduction in global histone levels, suggesting that Rrp1 and Rrp2 may modulate nucleosome dynamics. In addition we show that Rrp2, but not Rrp1, acts at telomeres. We propose that this role depends on the previously described interaction between Rrp2 and Top2. We conclude that Rrp1 and Rrp2 have important roles for centromere and telomere function and maintenance, contributing to the preservation of genome stability during vegetative cell growth. PLoS Genet. 8, e1002985. Choi, E. S., Cheon, Y., Kang, K. and Lee, D. (2017). The Ino80 complex mediates epigenetic centromere propagation via active removal of histone H3. Nat. Commun. 8, 529. . (2009). The role of novel genes rrp1(+) and rrp2(+) in the repair of DNA damage in Schizosaccharomyces pombe. DNA Repair (Amst). 8, 627-636. Involvement of Schizosaccharomyces pombe rrp1+ and rrp2 + in the Srs2-and Swi5/Sfr1-dependent pathway in response to DNA damage and replication inhibition.Allshire, R. C. (1996). Mutations in the fission yeast silencing factors clr4+ and rik1+ disrupt the localisation of the chromo domain protein Swi6p and impair centromere function.

Replication stress response in fission yeast differentially depends on maintaining proper levels of Srs2 helicase and Rrp1, Rrp2 DNA translocases

“…This was accompanied by the accumulation of mitotic aberrations (such as lagging and cut chromosomes), detected by microscopic examination of DAPI-stained cells (Fig. 4C) to a level that was comparable to that reported previously for cells overproducing Rrp1, but much lower than that observed for Rrp2 [7].…”

“…By scoring the number of red colonies on the medium with a limiting concentration of adenine we observed an increase in the loss of Ch16 mini-chromosome in srs2+ over-expressing cells (Fig. 4D), but two fold lower than reported earlier for Rrp1 and Rrp2 overproduction [7]. Overall, the effects of the upregulation of Srs2 are more similar to those for Rrp1 but less severe, especially than those caused by rrp2+ over-expression.…”

“…Together with the fact that overproduced Srs2 seems to localize predominantly in the nucleolus (Fig. 2D), while Rrp1 and Rrp2 are present at centromeres and telomeres [7], the above data indicate that upregulation of Srs2 levels may affects the cells in a way distinct from these translocases.…”

“…Previously we have found that even though rrp1Δ and rrp2Δ single mutants displayed very subtle phenotypes, over-expression of rrp1+ and rrp2+ genes allowed to identify novel biological functions for both proteins, at least partially independent from each other [7]. We thus decided to perform similar analysis for Srs2 protein.…”

“…It has been demonstrated in S. cerevisiae that an increase in Srs2 copy number is toxic in certain mutant contexts [19] and we have shown that overproduction of Rrp1 or Rrp2 causes viability loss in otherwise wild-type cells grown under unperturbed conditions [7]. In order to investigate the effect of srs2 + over-expression on cell growth, we have cloned the srs2+ gene under the nmt promoter into several pREP expression plasmids (Fig.…”