Histone acetylation in baker's yeast. Maintenance of the hyperacetylated configuration in log phase protoplasts.

The extent and rates of histone acetylation in the yeast Saccharomyces cerevisiae were investigated. The yeast histones are highly acetylated during log phase. The modification examined is not a function of polypeptide synthesis, but rather occurs on the histones subsequent to deposition. The log phase yeast histones are neither rapidly acetylated nor rapidly deacetylated. Acetylation and deacetylation rates for histones H3 and H4 are on the order of hours, indicating that, during log phase, these histones are maintained in the hyperacetylated form. The acetate turnover rate for H2B is somewhat increased over that observed for H3 and H4.