Subnuclear Relocalization of Structure-Specific Endonucleases in Response to DNA Damage

Abstract

Structure-specific endonucleases contribute to the maintenance of genome integrity by cleaving DNA intermediates that need to be resolved for faithful DNA repair, replication, or recombination. Despite advances in the understanding of their function and regulation, it is less clear how these proteins respond to genotoxic stress. Here, we show that the structure-specific endonuclease Mus81-Mms4/EME1 relocalizes to subnuclear foci following DNA damage and colocalizes with the endonucleases Rad1-Rad10 (XPF-ERCC1) and Slx1-Slx4. Recruitment takes place into a class of stress foci defined by Cmr1/WDR76, a protein involved in preserving genome stability, and depends on the E2-ubiquitin-conjugating enzyme Rad6 and the E3-ubiquitin ligase Bre1. Foci dynamics show that, in the presence of DNA intermediates that need resolution by Mus81-Mms4, Mus81 foci persist until this endonuclease is activated by Mms4 phosphorylation. Our data suggest that subnuclear relocalization is relevant for the function of Mus81-Mms4 and, probably, of the endonucleases that colocalize with it.

Cdc48 regulates intranuclear quality control sequestration of the Hsh155 splicing factor

“…INQ formation is driven by the small heat shock protein Hsp42, and the aggregase protein Btn2 (13), while INQ dissolution is regulated by Hsp104 and the Hsp70 system (9,11,12). Here we show that Cdc48 is also a stress-inducible component on INQ structures and that it plays an enzymatic role in INQ turnover.…”

Saccharomyces cerevisiae Mus81–Mms4 and Rad52 can cooperate in the resolution of recombination intermediates

“…This is supported by the fact that Rad52 is induced in response to DNA damaging agents (Cole, Schild, Lovett, & Mortimer, ). Moreover, in response to DNA damage, Mus81–Mms4 was shown to relocate to subnuclear foci with Rad1–Rad10 and Slx1–Slx4, and the relocalization corresponded to the function of Mus81–Mms4 endonuclease (Saugar, Jimenez‐Martin, & Tercero, ). In the G2/M phase, Mms4 is phosphorylated and the activity level of the Mus81 complex is enhanced to cope with the intermediates generated.…”

Resolvases, Dissolvases, and Helicases in Homologous Recombination: Clearing the Road for Chromosome Segregation

“…In the presence of recombination intermediates, Mus81-Mms4 foci persist until the nuclease is activated by Mms4 phosphorylation. Interestingly, other SSEs, such as Rad1-Rad10 and Slx1-Slx4, also colocalize with Mus81-Mms4 in these subnuclear foci suggesting that relocalization of SSEs could constitute another layer of regulation aimed not only to promote the efficient resolution of DNA intermediates, but also to prevent their untimely function [118].…”

“…Independently of the type of DNA substrate catalyzed, the main role of the Slx1-Slx4 heterodimer is to collaborate with Mus81-Mms4 and Rad1-Rad10 complexes to disentangle unresolved JMs generated during DNA repair (Figure 1). Consequently, these complexes colocalize at Cmr1 stress foci in response to DNA damage [118] and interact in genome-wide two-hybrid analysis [147]. Moreover, a mutant defective in Rad1-Rad10-Slx4 fails to repair a DSB generated at the mating type locus, presents an extended cell cycle delay in response to DNA damage and shows decreased viability during mating-type switching [148].…”