Exploring the topology of the Gid complex, the E3 ubiquitin ligase involved in catabolite-induced degradation of gluconeogenic enzymes

J Biol Chem. 2012 Jul 20;287(30):25602-14. doi: 10.1074/jbc.M112.363762. Epub 2012 May 29.

Abstract

In the yeast Saccharomyces cerevisiae, key regulatory enzymes of gluconeogenesis such as fructose-1,6-bisphosphatase are degraded via the ubiquitin proteasome system when cells are replenished with glucose. Polyubiquitination is carried out by the Gid complex, a multisubunit ubiquitin ligase that consists of seven different Gid (glucose-induced degradation-deficient) proteins. Under gluconeogenic conditions the E3 ligase is composed of six subunits (Gid1/Vid30, Gid2/Rmd5, Gid5/Vid28, Gid7, Gid8, and Gid9/Fyv10). Upon the addition of glucose the regulatory subunit Gid4/Vid24 appears, binds to the Gid complex, and triggers ubiquitination of fructose-1,6-bisphosphatase. All seven proteins are essential for this process; however, nothing is known about the arrangement of the subunits in the complex. Interestingly, each Gid protein possesses several remarkable motifs (e.g. SPRY, LisH, CTLH domains) that may play a role in protein-protein interaction. We, therefore, generated altered versions of individual Gid proteins by deleting or mutating these domains and performed co-immunoprecipitation experiments to analyze the interaction between distinct subunits. Thus, we were able to create an initial model of the topology of this unusual E3 ubiquitin ligase.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Motifs
  • Gluconeogenesis / physiology*
  • Glucose / chemistry
  • Glucose / genetics
  • Glucose / metabolism
  • Models, Molecular*
  • Multienzyme Complexes* / chemistry
  • Multienzyme Complexes* / genetics
  • Multienzyme Complexes* / metabolism
  • Mutation
  • Saccharomyces cerevisiae / enzymology*
  • Saccharomyces cerevisiae Proteins* / chemistry
  • Saccharomyces cerevisiae Proteins* / genetics
  • Saccharomyces cerevisiae Proteins* / metabolism
  • Ubiquitin-Protein Ligases* / chemistry
  • Ubiquitin-Protein Ligases* / genetics
  • Ubiquitin-Protein Ligases* / metabolism
  • Ubiquitination / physiology*

Substances

  • Multienzyme Complexes
  • Saccharomyces cerevisiae Proteins
  • Ubiquitin-Protein Ligases
  • Glucose