title: Growth-regulated formation of heteromeric complexes of the centromere and promoter factor, Cbf1p, in yeast.
abstract: Transcriptional regulation of the yeast cytochrome c1 gene (CYT1) in response to oxygen and carbon source is mediated by Haplp and the Hap2 complex. Furthermore, the centromere-binding factor 1 (Cbflp) associates with the CYT1 upstream region (UAS(CYT1)), but its direct activation potential is insignificant. The possible role of Cbflp as a modulator of transcriptional adaptation to changes in nutritional conditions was examined. In electrophoretic mobility shift assays (EMSA) using yeast nuclear extracts, Cbflp was found to exist as homo- and heterodimers of processed subforms of 54 and 37 kDa. An additional 18-kDa version was the only species found in anaerobic cells grown under an atmosphere of purified nitrogen, but not when CO2 was used to establish anaerobiosis. All three dimers of the 37 and 54 kDa versions of Cbflp that occurred in oxidatively growing cells gave rise to hetero-oligomeric complexes containing other as yet unidentified protein(s). Complex formation was not observed with extracts from cultures grown on high levels of glucose and was dependent on pre-assembly in the absence of target DNA. Pre-treatment with alkaline phosphatase enhanced formation of these higher-order complexes. The C-terminal 18-kDa segment of Cbflp, which can undergo dimerization and bind DNA, does not induce supershifts after preincubation and is not influenced by dephosphorylation. We propose that the N-terminal domain is subject to carbon source- or growth-dependent phosphorylation/dephosphorylation events that result in differential recruitment of additional factors to promoters of genes that encode proteins required for non-fermentative growth.
authors.affiliation: Institute for Genetics and Microbiology, Ludwig-Maximilians-Universität München, Munich, Germany.
authors.forename: U
authors.initials: U
authors.lastname: Oechsner
authors.forename: W
authors.initials: W
authors.lastname: Bandlow
mesh_terms: D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D001665:Binding Sites; D019757:Carbon-Oxygen Lyases / Q000235:genetics / Q000378:metabolism*; D003575:Cytochromes c1 / Q000235:genetics / Q000378:metabolism; D004271:DNA, Fungal / Q000235:genetics / Q000378:metabolism; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism / Q000494:pharmacology; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D014169:Transformation, Bacterial
chemical_list: D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; C064042:CBF1 protein, S cerevisiae; D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D003575:Cytochromes c1; D019757:Carbon-Oxygen Lyases; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D005947:Glucose