A Unifying Mechanism of DNA Translocation Underlying Chromatin Remodeling

Chromatin remodelers alter the position and composition of nucleosomes, and play key roles in the regulation of chromatin structure and various chromatin-based transactions. Recent cryo-electron microscopy (cryo-EM) and single-molecule fluorescence resonance energy transfer (smFRET) studies have shed mechanistic light on the fundamental question of how the remodeling enzymes couple with ATP hydrolysis to slide nucleosomes. Structures of the chromatin remodeler Snf2 bound to the nucleosome reveal the conformational cycle of the enzyme and the induced DNA distortion. Investigations on ISWI, Chd1, and INO80 support a unifying fundamental mechanism of DNA translocation. Finally, studies of the SWR1 complex suggest that the enzyme distorts the DNA abnormally to achieve histone exchange without net DNA translocation.