Interaction ofSaccharomyces cerevisiae Pho2 with Pho4 increases the accessibility of the activation domain of Pho4
- 48 Downloads
InSaccharomyces cerevisiae, expression of acid phosphatase, encoded by thePHO5 gene, requires two positive regulatory factors, Pho4 and Pho2 (also called Bas2 or Grf10). UsingGAL4-PHO4 fusions, we demonstrate that a functional interaction between these two proteins is necessary for transcriptional activation to occur. This functional interaction between Pho4 and Pho2 is independent of the presence of the negative regulatory factor, Pho80, which also interacts with Pho4. Interestingly, truncations of Pho4 missing amino acids 252–265, which encompass the basic region of the basic helix-loop-helix (bHLH) DNA binding motif, exhibit high transcriptional activation that is independent of the Pho2 molecule. Single amino acid mutations of highly conserved residues within this area all display this Pho2-independent phenotype. A region near the C-terminus of Pho2 appears to be critical for this interaction with Pho4. A model to account for the requirement for Pho2 in Pho4-dependent transcriptional activation is proposed.
Key wordsTranscription factors Gene expression Protein-protein interactionPHO4 PHO2 Saccharomyces cerevisiae
Unable to display preview. Download preview PDF.
- Daignan-Fornier B, Fink GR (1992) Coregulation of purine and histidine biosynthesis by the transcriptional activators Bas1 and Bas2. Proc Natl Acad Sci USA 89:6747–6750Google Scholar
- Dang C, Barrett J, Villa-Garcia M, Resar LM, Kato GJ, Rearon ER (1990) Intracellular leucine zipper interactions suggest c-Myc hetero-oligomerization. Mol Cell Biol 11:954–962Google Scholar
- Lemire JM, Wilcocks T, Halvorson HO, Bostian KA (1985) Regulation of repressible acid phosphatase gene transcription inSaccharomyces cerevisiae. Mol Cell Biol 5:2134–2141Google Scholar
- Oshima Y (1982) Regulatory circuits for gene expression: the metabolism of galactose and phosphate. In: Strathern JN, Gones EW, Broach JR (eds) The molecular biology of the yeastSaccharomyces cerevisiae, vol 3. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, New York, pp 159–180Google Scholar