HDA1 AND HDA3 ARE COMPONENTS OF A YEAST HISTONE DEACETYLASE (HDA) COMPLEX

Histone acetylation is maintained through the action of histone acetyl transferases and deacetylases and has been correlated with increased g ene activity. To investigate the functional role of these enzymes in t he regulation of transcription, we have purified from Saccharomyces ce revisiae two histone deacetylase activities, HDA and HDB, with molecul ar masses of similar to 350 and 600 kDa, respectively. In vitro, the H DA activity deacetylates all four core histones, has a preference for histone H3, and is strongly inhibited by trichostatin A (a specific in hibitor of histone deacetylases). HDB is considerably less sensitive t o trichostatin A. We report the extensive purification of the HDA acti vity and the identification of peptides (p75, p73, p72, and p71) whose presence correlates with deacetylase activity on native polyacrylamid e gels. An antibody to p75 immunoprecipitates peptides with molecular masses similar to those in the 350-kDa complex. Additionally, antibodi es to p75 and p71 specifically precipitate histone deacetylase activit y and coimmunoprecipitate each other. Gene disruptions of p75 (HDA1) o r p71 (HDA3) cause the loss of the 350-kDa (but not the 600-kDa) activ ity from our chromatography profiles. These data argue strongly that H DA1 and HDA3 are subunits of the HDA complex, which is structurally di stinct from the second, HDB complex.