Transcriptional regulator Leu3 of Saccharomyces cerevisiae: Separation of activator and repressor functions

Ji Ying Sze, Eumorphia Remboutsika, Gunter B. Kohlhaw

Research output: Contribution to journalArticle

24 Scopus citations

Abstract

The Leu3 protein of Saccharomyces cerevisiae binds to specific DNA sequences present in the 5′ noncoding region of at least five RNA polymerase II-transcribed genes. Leu3 functions as a transcriptional activator only when the metabolic intermediate α-isopropylmalate is also present. In the absence of α-isopropylmalate, Leu3 causes transcription to be repressed below basal levels. We show here that different portions of the Leu3 protein are responsible for activation and repression. Fusion of the 30 C-terminal residues of Leu3 to the DNA-binding domain of the Ga14 protein created a strong cross-species activator, demonstrating that the short C-terminal region is not only required but also sufficient for transcriptional activation. Using a recently developed Leu3-responsive in vitro transcription assay as a test system for repression (J. Sze, M. Woontner, J. Jaehning, and G. B. Kohlhaw, Science 258:1143-1145, 1992), we show that mutant forms of the Leu3 protein that lack the activation domain still function as repressors. The shortest repressor thus identified had only about 15% of the mass of the full-length Leu3 protein and was centered on the DNA-binding region of Leu3. Implications of this finding for the mechanism of repression are discussed.

Original languageEnglish (US)
Pages (from-to)5702-5709
Number of pages8
JournalMolecular and cellular biology
Volume13
Issue number9
DOIs
StatePublished - Sep 1993
Externally publishedYes

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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