Nucleosome Switching

We present a statistical-mechanical analysis of the positioning of nucleosomes along one of the chromosomes of yeast DNA as a function of the strength of the binding potential and of the chemical potential of the nucleosomes. We find a significant density of two-level nucleosome switching regions where, as a function of the chemical potential, the nucleosome distribution undergoes a "micro" first-order transition. The location of these nucleosome switches shows a strong correlation with the location of transcription-factor binding sites.