Swapping the gene-specific and regional silencing specificities of the Hst1 and Sir2 histone deacetylases.

Sir2 and Hst1 are NAD(+)-dependent histone deacetylases of budding yeast that are related by strong sequence similarity. Nevertheless, the two proteins promote two mechanistically distinct forms of gene repression. Hst1 interacts with Rfm1 and Sum1 to repress the transcription of specific middle-sporulation genes.

Alpha1-induced DNA bending is required for transcriptional activation by the Mcm1-alpha1 complex.

The yeast Mcm1 protein is a founding member of the MADS-box family of transcription factors that is involved in the regulation of diverse sets of genes through interactions with distinct cofactor proteins. Mcm1 interacts with the Matalpha1 protein to activate the expression of the alpha-cell type-specific genes. To understand the requirement of the cofactor alpha1 for Mcm1-alpha1-dependent transcriptional activation we analyzed the recruitment of Mcm1 to the promoters of alpha-specific genes in vivo and found that Mcm1 is able to bind to the promoters of alpha-specific genes in the absence of alpha1.

Interactions of the Mcm1 MADS box protein with cofactors that regulate mating in yeast.

The yeast Mcm1 protein is a member of the MADS box family of transcriptional regulatory factors, a class of DNA-binding proteins that control numerous cellular and developmental processes in yeast, Drosophila melanogaster, plants, and mammals. Although these proteins bind DNA on their own, they often combine with different cofactors to bind with increased affinity and specificity to their target sites. To understand how this class of proteins functions, we have made a series of alanine substitutions in the MADS box domain of Mcm1 and examined the effects of these mutations in combination with its cofactors that regulate mating in yeast.