Protein Involved in Minichromosome Maintenance in Yeast Binds a Transcriptional Enhancer Conserved in Eukaryotes.

摘要

The Saccharomyces cerevisiae MCM1 gene product is a protein with multiple functions. It is a transcription factor necessary for expression of mating-type-specific genes and is also required for the maintenance of minichromosomes. MCM1 shows DNA-binding specificities similar to those of two previously reported DNA-binding factors, pheromone/receptor transcription factor (PRTF) and general regulator of mating type (GRM); like PRTF, its activity can be modulated by the alpha 1 protein. MCM1 binds to the dyad symmetry element 5'-CCTAATTAGG and related sequences, which we refer to as MCM1 control elements (MCEs). MCEs are found within the regulatory regions of a- and alpha-specific genes. Direct and indirect DNA binding assays suggest that a conserved 5'-ATTAGG in one-half of the dyad symmetry element is important for MCM1 binding whereas variants in the other half are tolerated. We have used a novel DNase I 'nicking interference' assay to investigate the interaction of MCM1 with its substrate. These data suggest that MCM1 binds as a dimer, interacting symmetrically with the ATTAGG residue in each half of the binding site. Reprints. (jes)