Histone turnover marks the boundaries of cis-regulatory domains. Drosophila melanogaster

Cellular memory is maintained at the Drosophila homeotic gene clusters by cis-regulatory elements who mechanism of action is unknown. We have examined chromatin dynamics in the Drosophila genome by measuring histone turnover levels at high resolution. Surprisingly, homeotic gene clusters display characteristic histone turnover profiles with conspicuous peaks at boundaries of cis-regulatory domains superimposed over regions of very low turnover. Peaks of histone turnover precisely correspond to nuclease hypersensitive sites for epigenetic silencing proteins. Our results suggest that epigenetic regulation is facilitated by histone turnover, which maintains continuous accessibility ov cis-regulatory DNA. Keywords: Chromatin affinity-purification on microarray Overall design: Chromatin affinity profiling of histones H3 and H3.3 on Drosophila tiling arrays