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.

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Reference Type

Journal Article | Research Support, Non-U.S. Gov't

Authors

Menssen R, Schweiggert J, Schreiner J, Kusevic D, Reuther J, Braun B, Wolf DH

Primary Lit For

VID30 | VID28 | VID24 | RMD5 | FYV10 | GID7 | GID8 | GID E3 ubiquitin ligase complex, GID4 variant | GID E3 ubiquitin ligase complex, GID10 variant | GID E3 ubiquitin ligase complex, GID11 variant

Additional Lit For

Review For