Effect of nonenzymatic histone acetylation on chromatin high-order folding.

In the present study we have made attempts to estimate the effect of histone acetylation on the folding of the chromatin fibril into its high-order structures. Histones were modified directly in isolated nuclei using acetyl adenylate as an acetyl donor. High-order folding of acetylated chromatin was analyzed by titration with increasing amounts of ethidium bromide. We have shown that chromatin with non-enzymatically acetylated histones exhibits a less folded conformation when compared to intact chromatin. We discuss the molecular bases of this phenomenon and propose a novel generalized model for regulation of chromatin high-order folding.