The Role of Histone H1 in Saccharomyces cerevisiae

Linker histone H1 is a fundamental component of chromatin in eukaryotes with unclear functions in chromosome biology. We are utilizing genetic and biochemical approaches to determine the role of histone H1 in chromatin structure and function in Saccharomyces cerevisiae. First, we are assessing the effects of H1 gene deletions in strains with point mutations in core histones H3 and H4. With changes in silencing as a sensitive reporter for changes in chromatin, we are identifying H1's interaction with the nucleosome and overall function in chromatin. When H1 is deleted, we find a statistical overrepresentation of specific histone region mutations with the same silencing phenotype, such as the H3 tail deletions, suggesting that H1 is interacting with specific regions of the nucleosome. Through a biochemical lens, we are also addressing how histone H1 interacts structurally with DNA. To examine its binding specificity to DNA, we are examining histone H1's association with DNA four-way junctions in vitro. Through the approaches of genetics and structural biology, we will gain insight on the role of histone H1 in chromatin.