Intrinsically disordered histone tails are the terminal segments of the histone proteins, which regulate chromatin structure and dynamics.  We have carried out atomistic simulations for each of four histone tails, H4, H3, H2B and H2A, and probed their intrinsic conformational preferences finding organized states and specific flickering secondary structural elements. In particular, H4 forms beta hairpins, H3 and H2B adopt alpha helical elements, while H2A is fully disordered. We also investigated the way conformational preferences of the H4 tail change upon LYS-16 acetylation. Our  results, obtained from multiple atomistic molecular dynamics simulations, suggest significant changes in the secondary structure propensities of the free H4 tail upon acetylation and further transitions upon binding to DNA. Based on the results of our simulations, we propose a physical explanation for the way LYS-16 acetylation triggers the loosening of chromatin fibers, which was observed in a variety of experiments.

Secondary structure preferences of free histone tails and structural transitions induced upon binding to DNA

243rd National Meeting (2012)

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