Genetic and Biochemical Analysis of Chromatin Modulators in Yeast

Rutgers, The State University Of New Jersey-Rbhs-Robert Wood, Piscataway NJ

Investigators

Abstract

The metabolic activity of eukaryotic DNA is restricted by its packaging into chromatin. Accordingly, transcription, replication and repair require chromatin remodeling activities to allow factor access to template DNA. Two classes of chromatin remodeling activities have been described. One promotes ATP-dependent remodeling, as exemplified by the highly conserved and well-characterized SWI/SNF complex. The other class catalyzes covalent modification of the histones, primarily at their N-terminal tails. Histone acetylation, methylation, phosphorylation and ubiquitination have been described. Presumably these modifications weaken histone-DNA or nucleosome-nucleosome interactions, thereby allowing factor access to DNA. This project addresses the role of covalent chromatin modifiers in gene silencing. The premise of the project is that the novel Set2 and Hsl7 proteins directly catalyze histone modifications as components of chromatin modifying complexes. Three specific Aims are being pursued, exploiting a powerful combination of yeast genetics, biochemistry and genomics. Aim #1 is to identify factors that genetically interact with Set2 and Hsl7; Aim #2 is to isolate and define Set2 and Hsl7 complexes; Aim #3 is to define the interplay among histone methyltransferases, acetyltransferases, kinases and deacetylases. This project is based on the recent characterization of the effects of histone acetylation and deacetylation on silencing. The successful outcome of this project is likely to identify novel chromatin modifiers and to define how these factors interact to regulate gene expression. The genetic information in higher organisms is packaged into chromatin, a complex structure consisting of DNA and histone proteins. In the past several years several proteins have been identified that regulate gene expression by affecting chromatin structure. The goal of this project is to isolate and define new proteins that control gene expression by biochemically modifying histones. A powerful combination of genetics, biochemistry and genomics will be used in this project. Novel information gained from this study is likely to be generally applicable given that chromatin structure and known histone modifiers are highly conserved among different organisms.