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The Rsp5 ubiquitin ligase is coupled to and antagonized by the Ubp2 deubiquitinating enzyme
Author(s) -
Kee Younghoon,
Lyon Nancy,
Huibregtse Jon M
Publication year - 2005
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/sj.emboj.7600710
Subject(s) - deubiquitinating enzyme , ubiquitin ligase , dna ligase , ubiquitin , biology , microbiology and biotechnology , saccharomyces cerevisiae , mutant , enzyme , biochemistry , yeast , gene
Saccharomyces cerevisiae Rsp5 is an essential HECT ubiquitin ligase involved in several biological processes. To gain further insight into regulation of this enzyme, we identified proteins that copurified with epitope‐tagged Rsp5. Ubp2, a deubiquitinating enzyme, was a prominent copurifying protein. Rup1, a previously uncharacterized UBA domain protein, was required for binding of Rsp5 to Ubp2 both in vitro and in vivo . Overexpression of Ubp2 or Rup1 in the rsp5‐1 mutant elicited a strong growth defect, while overexpression of a catalytically inactive Ubp2 mutant or Rup1 deleted of the UBA domain did not, suggesting an antagonistic relationship between Rsp5 and the Ubp2/Rup1 complex. Consistent with this model, rsp5‐1 temperature sensitivity was suppressed by either ubp2 Δ or rup1 Δ mutations. Ubp2 reversed Rsp5‐catalyzed substrate ubiquitination in vitro , and Rsp5 and Ubp2 preferentially assembled and disassembled, respectively, K63‐linked polyubiquitin chains. Together, these results indicate that Rsp5 activity is modulated by being physically coupled to the Rup1/Ubp2 deubiquitinating enzyme complex, representing a novel mode of regulation for an HECT ubiquitin ligase.