Histone acetylation and deacetylation are important for gene regulation. The histone acetyltransferase, Gcn5, is an activator of transcriptional initiation that is recruited to gene promoters. Here, we map genome-wide Gcn5 occupancy and histone H3K14ac at high resolution. Gcn5 is predominantly localized to coding regions of highly transcribed genes, where it collaborates antagonistically with the class-II histone deacetylase, Clr3, to modulate H3K14ac levels and transcriptional elongation. An interplay between Gcn5 and Clr3 is crucial for the regulation of many stress-response genes. Our findings suggest a new role for Gcn5 during transcriptional elongation, in addition to its known role in transcriptional initiation.

BackgroundHistone acetyltransferase enzymes (HATs) are implicated in regulation of transcription. HATs from different families may overlap in target and substrate specificity.ResultsWe isolated the elp3+ gene encoding the histone acetyltransferase subunit of the Elongator complex in fission yeast and characterized the phenotype of an Δelp3 mutant. We examined genetic interactions between Δelp3 and two other HAT mutants, Δmst2 and Δgcn5 and used whole genome microarray analysis to analyze their effects on gene expression.ConclusionsComparison of phenotypes and expression profiles in single, double and triple mutants indicate that these HAT enzymes have overlapping functions. Consistent with this, overlapping specificity in histone H3 acetylation is observed. However, there is no evidence for overlap with another HAT enzyme, encoded by the essential mst1+ gene.

Background: Fission yeast cells undergo sexual differentiation in response to nitrogen starvation. In this process haploid M and P cells first mate to form diploid zygotes, which then enter meiosis and sporulate. Prior to mating, M and P cells communicate with diffusible mating pheromones that activate a signal transduction pathway in the opposite cell type. The pheromone signalling orchestrates mating and is also required for entry into meiosis.