Abstract
DEAE-Sepharose chromatography of extracts from Zea mays meristematic cells revealed multiple histone acetyltransferase and histone deacetylase enzyme forms. An improved method for nuclear isolation allowed us to discriminate nuclear and cytoplasmic enzymes. Two nuclear histone acetyltransferases, A1 and A2, a cytoplasmic B-enzyme and two nuclear histone deacetylases, HD1 and HD2, have been identified. The histone specificity of the different enzyme forms has been studied in an in vitro system, using chicken erythrocyte histones as substrate. The cytoplasmic histone acetyltransferase B is the predominant enzyme, which acetylates mainly histone H4 and to a lesser extent H2A. The nuclear histone acetyltransferase A1 preferentially acetylates H3 and also H4, whereas enzyme A2 is specific for H3. This substrate specificity was confirmed with homologous Z. mays histones. The two histone deacetylases differ from each other with respect to ionic strength dependence, inhibition by acetate and butyrate, and substrate specificity. The strong inhibitory effect of acetate on histone deacetylases was exploited to distinguish different histone acetyltransferase forms.
Highlights
From the Department of $Microbiology, University of Innsbruck, Medical School, A-6020, Innsbruck, Austria and the IIDeDartment of Biochemistrv and Molecular Biolo. mI“ ., Faculty of Sciences, University of Vakncia, E-46100 Burjaisot, Vakncia: Spain
The studies led to a classic grouping of histone acetyltransferases based on subcellular localization, chromatographic behavior, and histone specificity; according to this, histone acetyltransferaseA was characterized as a nuclear enzyme form which acetylateshistones in nucleosomes and all core histones in vitro, whereas histone acetylhistone deacetylases differ from each other with re- transferase B was defined as a cytoplasmic enzyme form not spect to ionic strength dependence, inhibition by ace- active with nucleosomes, which only acetylates histone H4
Sepharosecolumnwith a linear NH4C1 gradient,histone acetyltransferase and histonedeacetylase enzyme forms were fractionated into distinctpeaks
Summary
Soon after the discovery of reversible hisacetyltransferase and histone deacetylase enzyme toneacetylation the firsthistoneacetyltransferase activity forms. A2, a cytoplasmic B-enzyme and two nuclear histone deacetylases, HD1 and HD2, have been identified.
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