Extensive purification and characterization of chromatin-bound histone acetyltransferase from Saccharomyces cerevisiae.

A strong correlation has been established between reversible acetylation of histones and transcriptional activation of chromatin. However, the function of histone acetylation remains unknown. We have approached this question by purifying histone acetyltransferase 15,000-fold from yeast and characterizing it enzymatically. Biochemical properties, including the pH and temperature optima and the Michaelis-Menten constants for both acetyl coenzyme A and histones, are similar to those reported for histone acetyltransferases from higher eukaryotes. Yeast histone acetyltransferase has a native molecular weight of 110,000 as determined by gel filtration and is tightly bound to chromatin. It displays high-substrate specificity for histones. It acetylates all four core histones in the order: H4 greater than H2B greater than H2A. 10-fold higher histone acetyltransferase activity is observed for free histones when compared to yeast polynucleosomes as a substrate.