title: Physical and genetic associations of the Irc20 ubiquitin ligase with Cdc48 and SUMO.
abstract: A considerable percentage of the genome is dedicated to the ubiquitin-proteasome system, with the yeast genome predicted to encode approximately 100 ubiquitin ligases (or E3s), and the human genome predicted to encode more than 600 E3s. The most abundant class of E3s consists of RING finger-containing proteins. Although many insights have been obtained regarding the structure and catalytic mechanism of the E3s, much remains to be learned about the function of the individual E3s. Here we characterize IRC20, which encodes a dual RING- and Snf/Swi family ATPase domain-containing protein in yeast that has been implicated in DNA repair. We found that overexpression of IRC20 causes two transcription-associated phenotypes and demonstrate that the Irc20 RING domain possesses ubiquitin E3 activity in vitro. Two mass spectrometry approaches were undertaken to identify Irc20-associated proteins. Wild-type Irc20 associated with Cdc48, a AAA-ATPase that serves as an intermediary in the ubiquitin-proteasome system. A second approach using a RING mutant derivative of Irc20 detected increased association of the Irc20 mutant with SUMO. These findings provide a foundation for understanding the roles of Irc20 in transcription and DNA repair.
authors.affiliation: Department of Genetics, Albert Einstein College of Medicine, Bronx, New York, United States of America.
authors.forename: Aaron
authors.initials: A
authors.lastname: Richardson
authors.forename: Richard G
authors.initials: RG
authors.lastname: Gardner
authors.forename: Gregory
authors.initials: G
authors.lastname: Prelich
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D004265:DNA Helicases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D050505:Mutant Proteins / Q000737:chemistry / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D011485:Protein Binding; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D025841:Small Ubiquitin-Related Modifier Proteins / Q000378:metabolism*; D058207:Sumoylation; D014158:Transcription, Genetic; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*; D000074405:Valosin Containing Protein
chemical_list: D018797:Cell Cycle Proteins; D050505:Mutant Proteins; D029701:Saccharomyces cerevisiae Proteins; D025841:Small Ubiquitin-Related Modifier Proteins; D044767:Ubiquitin-Protein Ligases; D000251:Adenosine Triphosphatases; C574661:Irc20 protein, S cerevisiae; C000614177:CDC48 protein, S cerevisiae; D004265:DNA Helicases; D000074405:Valosin Containing Protein