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  • The EMBO Journal (2000) 19, 2161 - 2167
  • doi:10.1093/emboj/19.10.2161

Ubc8p functions in catabolite degradation of fructose-1,6-bisphosphatase in yeast

Thomas Schüle1, Matthias Rose2, Karl-Dieter Entian2, Michael Thumm1 and Dieter H. Wolf1

  1. Institut für Biochemie, Universität Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
  2. Institut für Mikrobiologie, Johann Wolfgang Goethe-Universität Frankfurt, Marie-Curie-Stras zlige 9, 60439 Frankfurt, Germany

Correspondence to:

Dieter H. Wolf, E-mail: dieter.wolf@po.uni-stuttgart.de

Received 26 January 2000; Accepted 21 March 2000; Revised 14 March 2000

The key gluconeogenic enzyme fructose-1,6-bisphosphatase (FBPase) is synthesized when cells of the yeast Saccharomyces cerevisiae are grown on a non-fermentable carbon source. After shifting the cells to glucose-containing medium, in a process called catabolite degradation, FBPase is selectively and rapidly broken down. We have isolated gid mutants, which are defective in this glucose-induced degradation process. When complementing the defect in catabolite degradation of FBPase in gid3-1 mutant cells with a yeast genomic library, we identified the GID3 gene and found it to be identical to UBC8 encoding the ubiquitin-conjugating enzyme Ubc8p. The in vivo function of Ubc8p (Gid3p) has remained a mystery so far. Here we demonstrate the involvement of Ubc8p in the glucose-induced ubiquitylation of FBPase as a prerequisite for catabolite degradation of the enzyme via the proteasome. Like FBPase, Ubc8p is found in the cytoplasmic fraction of the cell. We demonstrate cytoplasmic degradation of FBPase.

  • Keywords:

    • catabolite degradation,
    • fructose-1,6-bisphosphatase,
    • GID,
    • Ubc8p,
    • ubiquitin