Histone Modifying Enzymes and Transcription

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DESCRIPTION (provided by applicant): The long term goal of this research is to understand the role of histone modifications such as acetylation and methylation and their effect on chromosome function, using the widely-studied yeast, Saccharomyces cerevisiae, to study these processes. In particular this grant will focus on the effect of histone modifications on transcription. The grant has 3 aims. The first one (1) focuses on how the cyclin-dependent kinase Bur1 controls methylation of histone H3 lysine 36 by the histone methylase Set2. Set2 is known to be associated with RNA polymerase II during transcriptional elongation, and we think that Bur1 controls a crucial step in the elongation process, acting through Set2. The second aim is concerned with using mass spectroscopy on highly purified yeast histones H2A and H2B to identify modifications such as acetylation and methylation of lysine residues. Once specific modified residues have been identified, the effects of mutating them will be investigated and the enzymes responsible for the modifications will be determined. The third aim is to study Spt10, a protein known to be important for transcription of histone genes and perhaps other genes. Spt10 is thought to be an N-acetyltransferase based on its sequence, but its substrate may not be histones. A novel method involving peptide libraries will be used to identify the protein(s) that Spt10 acetylates. Since histones and their modifications are highly conserved from yeast to humans, as is the process of gene expression, these studies will lead to a greater understanding of fundamental functions of chromosomes in human cells.