Issue Date: April 2, 2012
Histone Acetylation Allows DNA Unpacking
Acetylation of the tail of histone protein H4 is a key modification known to play a role in activating gene expression. Structural modeling studies by Garegin A. Papoian and Davit Potoyan of the University of Maryland now illuminate how the modification may work. To pack into chromosomes, DNA wraps around histone octamers, and the DNA-histone complexes further coil into fibers. Although histone tails are intrinsically disordered, Papoian and Potoyan still find that the proteins have conformational preferences. Unacetylated, the H4 tail of a DNA-histone complex can stretch out to interact with adjacent complexes, perhaps facilitating fiber formation, Papoian suggested. Acetylation of the tail at a lysine residue, however, induces a more compact structure that causes the tail to interact more strongly with its own DNA. The acetylated tail would then be unavailable for complex-complex interactions and would enable gene expression by allowing DNA-histone fibers to unwind.
C&EN Covers The ACS National Meeting
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