Slx5 and Slx8 are heterodimeric RING-domain-containing proteins that possess SUMO-targeted ubiquitin ligase (STUbL) activity in vitro. Slx5-Slx8 and its orthologs are proposed to target SUMO conjugates for ubiquitin-mediated proteolysis, but the only in vivo substrate identified to date is mammalian PML, and the physiological importance of SUMO-targeted ubiquitylation remains largely unknown. We previously identified mutations in SLX5 and SLX8 by selecting for suppressors of a temperature-sensitive allele of MOT1, which encodes a regulator of TATA-Binding Protein. Here we demonstrate that Mot1 is SUMOylated in vivo and that disrupting the Slx5-Slx8 pathway by mutation of the target lysines in Mot1, by deletion of SLX5 or the ubiquitin E2 UBC4, or by inhibition of the proteosome, suppresses mot1-301 mutant phenotypes and increases the stability of the Mot1-301 protein. The Mot1-301 mutant protein is targeted for proteolysis by SUMOylation to a much greater extent than wild-type Mot1, suggesting a quality control mechanism. In support of this idea, growth of yeast in the presence of the arginine analog canavanine results in increased SUMOylation and Slx5-Slx8-mediated degradation of wild-type Mot1. These results therefore demonstrate that Mot1 is an in vivo STUbL target in yeast and suggest a role for SUMO-targeted degradation in protein quality control.
|Evidence ID||Analyze ID||Interactor||Interactor Systematic Name||Interactor||Interactor Systematic Name||Type||Assay||Annotation||Action||Modification||Phenotype||Source||Reference||Note|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Gene Ontology Term||Gene Ontology Term ID||Qualifier||Aspect||Method||Evidence||Source||Assigned On||Reference||Annotation Extension|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Phenotype||Experiment Type||Experiment Type Category||Mutant Information||Strain Background||Chemical||Details||Reference|
|Evidence ID||Analyze ID||Regulator||Regulator Systematic Name||Target||Target Systematic Name||Experiment||Conditions||Strain||Source||Reference|