Structural Dynamics of Nucleosomes and Chromatin upon Transcription

The presence of histones on specific DNA sequences and the arrangement of histone-binding sites on nucleosomal DNA (nucleosome primary organization) have been tested by DNA — protein crosslinking developed in this laboratory [1]. Complete removal of histone H1 and partial or total depletion of core histones, depending on the level of transcription, were demonstrated for transcriptionallyactive genes of Drosophila coding for heat-shock proteins, hsp 70, using the “protein image” hybridization technique [2]. These structural transitions in chromatin were shown to occur only within the promoter and transcribed regions of the genes.