MUS81 encodes a novel Helix-hairpin-Helix protein involved in the response to UV- and methylation-induced DNA damage in Saccharomyces cerevisiae

Abstract

The gene MUS81 p6ethyl methansulfonate, UV sensitive) was identified as clone 81 in a two-hybrid screen using the Saccharomyces cerevisiae Rad54 protein as a bait. It encodes a novel protein with a predicted molecular mass of 72,316 (632 amino acids) and contains two helix-hairpin-helix motifs, which are found in many proteins involved in DNA metabolism in bacteria, yeast, and mammals. Mus81p also shares homology with motifs found in the XPF endonuclease superfamily. Deletion of MUS81 caused a recessive methyl methansulfonate- and UV-sensitive phenotype. However, mus81delta cells were not significantly more sensitive than wild-type to gamma-radiation or double-strand breaks induced by HO endonuclease. Double mutant analysis suggests that Rad54p and Mus81p act in one pathway for the repair of, or tolerance to, UV-induced DNA damage. A complex containing Mus81p and Rad54p was identified in immunoprecipitation experiments. Deletion of MUS81 virtually eliminated sporulation in one strain background and reduced sporulation and spore viability in another. Potential homologs of Mus81p have been identified in Schizosaccharomyces pombe, Caenorhabditis elegans and Arabidopsis thaliana. We hypothesize that Mus81p plays a role in the recognition and/or processing of certain types of DNA damage (caused by UV and MMS) during repair or tolerance processes involving the recombinational repair pathway.

Human Rad54 protein stimulates human Mus81–Eme1 endonuclease

“…Interaction between Rad54 and Mus81 was shown by using a 2-hybrid method and immunoprecipitation (8). Here, we demonstrated physical interactions between purified hRad54 and hMus81-Eme1 by using an affinity pull-down assay (Fig.…”

“…Thus, Mus81-Eme1 presents a subclass of HJ resolvases that differ from classical RuvC-like resolvases. However, the significance of the differences remains to be further elucidated.An important HR protein that physically interacts with Mus81 is Rad54 (8,11,14). Interestingly, Mus81 protein was first identified in S. cerevisiae through a 2-hybrid screen using Rad54 as the bait (8).…”

“…An important HR protein that physically interacts with Mus81 is Rad54 (8,11,14). Interestingly, Mus81 protein was first identified in S. cerevisiae through a 2-hybrid screen using Rad54 as the bait (8).…”

“…All of the defects in S. pombe mus81 mutants were rescued by expression of RusA, a bacteriophage resolvase that is highly specific for HJs (7). Mus81 protein is widely conserved among eukaryotes, including Saccharomyces cerevisiae (8), S. pombe (6), Arabidopsis thaliana (9), mice (10,11), and humans (12). Mus81 is related to the XPF family of structure-specific endonucleases, which share a highly conserved motif (V/IERKX 3 D) that constitutes an integral part of the endonuclease catalytic site.…”

“…Interestingly, Mus81 protein was first identified in S. cerevisiae through a 2-hybrid screen using Rad54 as the bait (8). Moreover, an S. cerevisiae mus81rad54 double mutant was viable and no more UV-sensitive than the rad54 single mutant, indicating that rad54 is epistatic to mus81 for UV sensitivity and that both proteins act in the same pathway for the tolerance/repair of UV-induced damage.…”