IDENTIFICATION OF MAIZE HISTONE DEACETYLASE HD2 AS AN ACIDIC NUCLEOLAR PHOSPHOPROTEIN

The steady state of histone acetylation is established and maintained by multiple histone acetyltransferases and deacetylases, and this stea dy state affects chromatin structure and function. The identification of a maize complementary DNA encoding the chromatin-bound deacetylase HD2 is reported. This protein was not homologous to the yeast RPD3 tra nscriptional regulator. It was expressed throughout embryo germination in correlation with the proliferative activity of cells. Antibodies a gainst recombinant HD2-p39 immunoprecipitated the native enzyme comple x, which was composed of phosphorylated p39 subunits. Immunofluorescen ce microscopy and sequence homologies suggested nucleolar localization . HD2 is an acidic nucleolar phosphoprotein that might regulate riboso mal chromatin structure and function.