title: Binding to Elongin C inhibits degradation of interacting proteins in yeast.
abstract: Elongin C is a highly conserved, low molecular weight protein found in a variety of multiprotein complexes in human, rat, fly, worm, and yeast cells. Among the best characterized of these complexes is a mammalian E3 ligase that targets proteins for ubiquitination and subsequent degradation by the 26 S proteasome. Despite its crucial role as a component of such E3 ligases and other complexes, the specific function of Elongin C is unknown. In yeast, Elongin C is a non-essential gene and there is no obvious phenotype as associated with its absence. We previously reported that in Saccharomyces cerevisiae Elongin C (Elc1) interacts specifically and strongly with a class of proteins loosely defined as stress response proteins. In the present study, we examined the role of yeast Elc1 in the turnover of two of these binding partners, Snf4 and Pcl6. Deletion of Elc1 resulted in decreased steady-state levels of Snf4 and Pcl6 as indicated by Western blot analysis. Northern blot analysis of mRNA prepared from elc1 null and wild type strains revealed no difference in mRNA levels for Snf4 and Pcl6 establishing that the effects of Elc1 are not transcriptionally mediated. Reintroduction of either yeast or human Elongin C into Elc1 null strains abrogated this effect. Taken together, these data document that the levels of Snf4 and Pcl6 are dependent on the presence of Elc1 and that binding to Elc1 inhibits the degradation of these proteins. The results suggest a new function for yeast Elongin C that is distinct from a direct role in targeting proteins for ubiquitination and subsequent proteolysis.
authors.affiliation: Department of Biochemistry, Tulane University Health Science Center, New Orleans, Louisiana 70112, USA. lhyman@tulane.edu
authors.forename: Linda E
authors.initials: LE
authors.lastname: Hyman
authors.forename: Edward
authors.initials: E
authors.lastname: Kwon
authors.forename: Sumana
authors.initials: S
authors.lastname: Ghosh
authors.forename: Jennifer
authors.initials: J
authors.lastname: McGee
authors.forename: Anna M Boguszewska
authors.initials: AM
authors.lastname: Chachulska
authors.forename: Tanya
authors.initials: T
authors.lastname: Jackson
authors.forename: William H
authors.initials: WH
authors.lastname: Baricos
mesh_terms: D000818:Animals; D017124:Conserved Sequence; D003546:Cysteine Endopeptidases / Q000378:metabolism; D000075065:Elongin; D005656:Fungal Proteins / Q000378:metabolism*; D006360:Heat-Shock Proteins / Q000378:metabolism*; D009097:Multienzyme Complexes / Q000378:metabolism; D010641:Phenotype; D046988:Proteasome Endopeptidase Complex; D011485:Protein Binding; D051381:Rats; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: C000616395:ELOC protein, human; C000616400:Eloc protein, rat; D000075065:Elongin; D005656:Fungal Proteins; D006360:Heat-Shock Proteins; D009097:Multienzyme Complexes; D014157:Transcription Factors; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex