IDENTIFICATION AND CHARACTERIZATION OF AN RPD3 HOMOLOG FROM MAIZE (ZEA-MAYS L.) THAT IS ABLE TO COMPLEMENT AN RPD3 NULL MUTANT OF SACCHAROMYCES-CEREVISIAE

In mammals, yeast and Drosophila, the histone deacetylase RPD3 protein s can alter the expression of genes involved in fundamental biological processes by affecting the degree of acetylation of histones and chan ging chromatin structure. Here we report the isolation of a cDNA seque nce encoding an RPD3 homologue from maize, which is able to complement the phenotype of an rpd3 null mutant of the yeast Saccharomyces cerev isiae. The expression of the corresponding gene(s) was assessed in dif ferent maize tissues. The number of homologous loci was estimated by S outhern hybridisation to be in the range of two to three, and the chro mosomal location of one of these loci was determined. Phylogenetic ana lysis and tests for relative divergence rates, using related RPD3 sequ ences from different species, were performed, and suggest that differe nt polymorphic forms of RPD3-like proteins that evolve at distinct rat es are present in the species considered.