Question

Role of chromatin in regulating gene expression and gene silencing

Answer 1

The long-term objective of this project is to learn more about how chromatin structure regulates transcriptional gene silencing in eukaryotes. The basic mechanisms used to generate inactive or silent chromatin are largely conserved in eukaryotic organisms ranging from yeast to humans. Our studies focus on understanding the roles of chromatin-associated factors, such as histones, histone-modifying enzymes, and silencing proteins, in regulating the silencing of RNA polymerase II-transcribed genes located in the ribosomal DNA locus (rDNA) of the budding yeast Saccharomyces cerevisiae. The experiments in this proposal will use a combination of genetic, molecular, and biochemical approaches to address how histones and silencing factors affect gene silencing and chromatin structure in the rDNA. First, studies to characterize the histone H3 methyltransferase complex, COMPASS, will be performed. Gene silencing is one of the only cases in S. cerevisiae, where H3 methylation has a clear effect on gene expression. The proposed experiments will investigate the role of COMPASS proteins in rDNA silencing, determine how rDNA chromatin is altered by methylation of histone H3, and address the possibility that