Abstract
We have revealed that distinct DNase I hypersensitive site (DNase I HS) was found in competent (expressed or inducible) gene promoter and was not found in incompetent (unexpressed nor inducible) gene promoters in Arabidopsis. Next, to understand the regulatory roles of histone modifications in transcriptional activation and competence, we performed chromatin immunoprecipitation analysis. Chromatin structural analysis of the heat-inducible HSP18.2 promoter revealed that the DNase I HS was pre-formed upstream of the cis-acting element in its inactive state, upon activation, histone H3 and H4 were acetylated, nucleosome(s) downstream of this DNase I HS was disrupted resulting in the exposure of the cis-elements and transcription start site. These results suggest that the DNase I HSs regulate transcription by providing accessible sites for the binding of chromatin remodeling factors. Regulatory roles of the presence of the DNase I HS, transcription factor binding and histone modification states will be discussed.
