The abundance of Met30p limits SCF(Met30p) complex activity and is regulated by methionine availability

D. B. Smothers, L. Kozubowski, C. Dixon, M. G. Goebl, N. Mathias

Research output: Contribution to journalArticle

23 Scopus citations


Ubiquitin-mediated degradation plays a crucial role in many fundamental biological pathways, including the mediation of cellular responses to changes in environmental conditions. A family of ubiquitin ligase complexes, called SCF complexes, found throughout eukaryotes, is involved in a variety of biological pathways. In Saccharomyces cerevisiae, an SCF complex contains a common set of components, namely, Cdc53p, Skp1p, and Hrt1p. Substrate specificity is defined by a variable component called an F-box protein. The F- box is a ~40-amino-acid motif that allows the F-box protein to bind Skp1p. Each SCF complex recognizes different substrates according to which F-box protein is associated with the complex. In yeasts, three SCF complexes have been demonstrated to associate with the ubiquitin-conjugating enzyme Cdc34p and have ubiquitin ligase activity. F-box proteins are not abundant and are unstable. As part of the SCF(Met30p) complex, the F-box protein Met30p represses methionine biosynthetic gene expression when availability of L-methionine is high. Here we demonstrate that in vivo SCF(Met30p) complex activity can be regulated by the abundance of Met30p. Furthermore, we provide evidence that Met30p abundance is regulated by the availability of L-methionine. We propose that the cellular responses mediated by an SCF complex are directly regulated by environmental conditions through the control of F-box protein stability.

Original languageEnglish (US)
Pages (from-to)7845-7852
Number of pages8
JournalMolecular and cellular biology
Issue number21
StatePublished - 2000

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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