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Regulation by Ubiquitination Without Degradation

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Science's STKE  08 Aug 2000:
Vol. 2000, Issue 44, pp. tw1
DOI: 10.1126/stke.2000.44.tw1

Ubiquitination is best known for tagging proteins for degradation by the proteasome. SCF complexes are involved in conferring substrate specificity to the E2 ubiquitin-conjugating enzymes. MET genes are involved in the regulation of methionine metabolism in yeast. Kaiser et al. used a genetic approach to determine that cell-cycle arrest in met30 mutants was due to hyperactivity of the Met4 transcription factor. Met30 is part of an SCF complex, and Met30 was required for ubiquitination of Met4; however, the stability of Met4 was unaffected by this posttranslational modification. Chromatin precipitation assays indicate that Met4 is constitutively associated with its target promoters, but that the ubiquitination of Met4 regulates its interaction with the transcription factor Cbf1. Thus, ubiquitination of Met4 is promoted by SCFMet30, which, instead of leading to its degradation, alters the transcriptional activity of Met4 by inhibiting its ability to recruit a second transcriptional regulator, Cbf1.

Kaiser, P., Flick, K., Wittenberg, C., and Reed, S. I. (2000) Regulation of transcription by ubiquitination without proteolysis: Cdc34/SCFMet30-mediated inactivation of the transcription factor Met4. Cell 102: 303-314. [Online Journal]