title: Quality control of a transcriptional regulator by SUMO-targeted degradation.
abstract: 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 Saccharomyces cerevisiae 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.
authors.affiliation: Department of Genetics, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, USA.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Wang
authors.forename: Gregory
authors.initials: G
authors.lastname: Prelich
mesh_terms: D000251:Adenosine Triphosphatases; D000595:Amino Acid Sequence; D002172:Canavanine / Q000494:pharmacology; D004265:DNA Helicases / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D055550:Protein Stability / Q000187:drug effects; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism*; D025841:Small Ubiquitin-Related Modifier Proteins / Q000378:metabolism*; D013379:Substrate Specificity / Q000187:drug effects; D035381:TATA-Binding Protein Associated Factors / Q000737:chemistry / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects; D025801:Ubiquitin / Q000378:metabolism
chemical_list: D050505:Mutant Proteins; D029701:Saccharomyces cerevisiae Proteins; D025841:Small Ubiquitin-Related Modifier Proteins; D035381:TATA-Binding Protein Associated Factors; D025801:Ubiquitin; D002172:Canavanine; D046988:Proteasome Endopeptidase Complex; D000251:Adenosine Triphosphatases; C073676:MOT1 protein, S cerevisiae; D004265:DNA Helicases