Abstract
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.
Highlights
We haveap- histone acetylation has had small effects on the stabilities of proached this question by purifyinghistone acetyl- nucleosome cores and higher levels of chromatin structure
Matin.Itdisplayshigh-substrate specificity for his- not be exclusively associated with active genes
Correlations between histone acetylation and mRNA that is transcribed in higher eukaryotes, a large fraction of production werereviewed by Allfrey (l),withmore recent the yeast genome is transcriptionally active [14]
Summary
$ Supported by the Veterans Administration Southwest Regional Epilepsy Center, Neurology Service, Veterans Administration Wadsworth Medical Center. Homogenized in 40 ml of Storage Buffer (5 mM Tris, pH 8.0,5mM 2- The relative specific activities of acetate incorporation into histone mercaptoethanol, 0.25 mM EDTA, and 10%glycerol) containing 400 types were determined from the staining pattern and fluorograph of mM NaCI. Extraction andacetoneprecipitation [26].Polynucleosomeswere pre- Linear salt gradient elution again resulted in a single sharp pared by Dounce homogenizing a chromatin sampilne storage buffer peak of activity at 550 mM NaCl (Fig. 3). In this experiment containing400 mM NaCI, centrifuging, and retainintghe pellet.
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