IDENTIFICATION OF THE YEAST METHIONINE BIOSYNTHETIC GENES THAT REQUIRE THE CENTROMERE-BINDING FACTOR-1 FOR THEIR TRANSCRIPTIONAL ACTIVATION

The yeast Centromere binding factor I (Cbf1) belongs to the family of the DNA binding factors that recognize the consensus sequence CACGTG. Phenotypic studies of cells lacking Cbf1 revealed that this factor is actually involved in two cellular processes; the fidelity of the chrom osomal segregation and the metabolism of sulfur amino acids. However, the function of Cbf1 in the regulation of the sulfur amino acid metabo lism is now a matter of controversy in literature with conflicting rep orts about its binding to the CACGTG sequences found upstream to the m ethionine biosynthetic genes. To provide a reliable basis for the func tional analysis of Cbf1, we present an analysis of the transcription o f the methionine biosynthesic genes in cells lacking Cbf1. Our results prove that Cbf1 is indeed involved in the transcriptional regulation of the sulfur amino acid metabolism.