NSF Award
9986650
The identification of ubiquitinated H2B (uH2B) in the yeast Saccharomyces cerevisiae and the discovery of phenotypes associated with its absence will be exploited to understand the role of this histone modification in chromosome structure and function. The overall objectives are to define the biological processes that depend on uH2B and to learn how this modification is regulated in vivo. The first goal is to determine whether uH2B is a chromatin constituent, since the subcellular localization of uH2B may determine its biological functions. General chromatin association will be measured in preparations that enrich for chromatin-associated proteins and after purification of nucleosomes, using a novel method of immunological detection. Preferential chromatin association of uH2B with specific genes will be assayed by the method of chromatin immunoprecipitation (ChIP). <br/> The modulation of chromatin structure by the posttranslational modification of histones has emerged as a key mechanism to regulate chromosome function in eukaryotes. Although a wealth of studies have investigated how transcriptional regulation is affected by histone acetylation, the biological roles of other histone modifications remain largely unknown. The discovery that uH2B is present in yeast and required for optimal cell growth and meiosis has provided a unique opportunity to study the impact of this modification in a genetically tractable organism. Since histone ubiquitination is an evolutionarily conserved process, it is expected that these studies will make significant contributions to our understanding of how this modification influences the multiple processes that occur on eukaryotic chromosomes.
