The role of H2A.Z and H2A.Z acetylation in gene regulation and gene expression in Saccharomyces cerevisiae

H2A.Z is a histone H2A variant that is conserved from yeast to humans, and is found at 63% of promoters in S. cerevisiae. This pattern of localization suggests that H2A.Z is somehow important for gene expression or regulation. H2A.Z can be acetylated at up to four lysine residues on its amino-terminal tail, and acetylated-H2A.Z is enriched in chromatin containing promoters of active genes. I investigated whether H2A.Z's role in GAL1 gene regulation and gene expression depends on H2A.Z acetylation. My findings suggested that H2A.Z functioned both in gene regulation and in gene expression and that only its role in gene regulation depended upon its acetylation. My findings also refuted earlier claims that H2A.Z has a role in GAL1-transcriptional memory. Additionally, my findings provided a revised view of the phenotypes of htz1Delta mutants: in the absence of H2A.Z, the SWR1 complex, which deposits H2A.Z into chromatin, was deleterious to the cell, and many of the phenotypes of cells lacking H2A.Z were due to the SWR1 complex's activity rather than to the absence of H2A.Z per se. These results indicate the need to re-evaluate all studies on the phenotypes of cells lacking H2A.Z.