Histone Acetylation, Not Stoichiometry, Regulates Linker Histone Binding in .

Linker histones play a fundamental role in shaping chromatin structure, but how their interaction with chromatin is regulated is not well understood. In this study, we used a combination of genetic and genomic approaches to explore the regulation of linker histone binding in the yeast, We found that increased expression of Hho1, the yeast linker histone, resulted in a severe growth defect, despite only subtle changes in chromatin structure. Further, this growth defect was rescued by mutations that increase histone acetylation.

Divergent Residues Within Histone H3 Dictate a Unique Chromatin Structure in Saccharomyces cerevisiae.

Histones are among the most conserved proteins known, but organismal differences do exist. In this study, we examined the contribution that divergent amino acids within histone H3 make to cell growth and chromatin structure in Saccharomyces cerevisiae. We show that, while amino acids that define histone H3.

Histone acetylation: truth of consequences?

Eukaryotic DNA is packaged into a nucleoprotein structure known as chromatin, which is comprised of DNA, histones, and nonhistone proteins. Chromatin structure is highly dynamic, and can shift from a transcriptionally inactive state to an active form in response to intra- and extracellular signals. A major factor in chromatin architecture is the covalent modification of histones through the addition of chemical moieties, such as acetyl, methyl, ubiquitin, and phosphate groups.

Acetylation of Rsc4p by Gcn5p is essential in the absence of histone H3 acetylation.

Rsc4p, a subunit of the RSC chromatin-remodeling complex, is acetylated at lysine 25 by Gcn5p, a well-characterized histone acetyltransferase (HAT). Mutation of lysine 25 does not result in a significant growth defect, and therefore whether this modification is important for the function of the essential RSC complex was unknown. In a search to uncover the molecular basis for the lethality resulting from loss of multiple histone H3-specific HATs, we determined that loss of Rsc4p acetylation is lethal in strains lacking histone H3 acetylation.