A COMPARATIVE-STUDY OF HISTONE DEACETYLASES OF PLANT, FUNGAL AND VERTEBRATE CELLS

The enzymatic equilibrium of reversible core histone acetylation is ma intained by two enzyme activities, histone acetyltransferase and histo ne deacetylase (HD). These enzyme activities exist as multiple enzyme forms. The present report describes methods to extract different HD-fo rms from three organisms, germinating maize embryos, the myxomycete Ph ysarum polycephalum, and chicken red blood cells; it provides data on the chromatographic separation and partial purification of HD-forms. I n germinating maize embryos three HDs (HD1-A, HD1-B, HD2) can be discr iminated; HD1-A, HD1-B, and HD2 were characterized in terms of their d ependence on pH, temperature and various ions, as well as kinetic para meters (k(M) for core histones) and inhibition by various compounds. T he same parameters were investigated for the corresponding enzymes of Physarum polycephalum, and mature and immature chicken erythrocytes. B ased on these results, optimum assay conditions were established for t he different enzyme forms. The kinetic data revealed that the maize hi stone deacetylase HD1-B peak after partial purification by Q-Sepharose chromatography was heterogeneous and consisted of two histone binding sites that differed significantly in their affinity for purified core histones. Optimized affinity chromatography on poly-Lysine Agarose in deed showed that the former defined deacetylase HD1-B can be separated clearly into two individual HD enzyme forms. The high multiplicity of histone deacetylases underlines the importance of these enzymes for t he complex regulation of core histone acetylation.