Abstract
Gene expression in eukatyotic cells involves the interaction of proteins with DNA packaged into nucleosomes: the primary structural units of chromatin. Recent sutudies show that transcription is regulated by multiple-steps of chromatin alteration, and that chromatin remodeling complexes are mainly responsible for the chromatin alteration from inactive state to destabilized state. Destabilization of nucleosomes was also found to occur in vivo at specific DNA sequences which can adopt non-B DNA structures. Hence, the nucleosome destabilizing sequences could be involved in the establishment of promoters that preset chromatin structure accessible for trans-acting factors prior to activation. Finally, organization of repressive chromatin structure by repressors in conjunction with global transcriptional regulators is described.
