Molecular Cell
Volume 57, Issue 5, 5 March 2015, Pages 850-859
Journal home page for Molecular Cell

Article
A Nucleotide-Driven Switch Regulates Flanking DNA Length Sensing by a Dimeric Chromatin Remodeler

https://doi.org/10.1016/j.molcel.2015.01.008Get rights and content
Under an Elsevier user license
open archive

Highlights

  • The HSS domain helps avoid a tug-of-war between protomers in a SNF2h dimer

  • Nucleotide state controls HSS domain binding to flanking DNA versus nucleosome core

  • Selectively impairing DNA length sensing abolishes mononucleosome centering

Summary

The ATP-dependent chromatin assembly factor (ACF) spaces nucleosomes to promote formation of silent chromatin. Two copies of its ATPase subunit SNF2h bind opposite sides of a nucleosome, but how these protomers avoid competition is unknown. SNF2h senses the length of DNA flanking a nucleosome via its HAND-SANT-SLIDE (HSS) domain, yet it is unclear how this interaction enhances remodeling. Using covalently connected SNF2h dimers we show that dimerization accelerates remodeling and that the HSS contributes to communication between protomers. We further identify a nucleotide-dependent conformational change in SNF2h. In one conformation the HSS binds flanking DNA, and in another conformation the HSS engages the nucleosome core. Based on these results, we propose a model in which DNA length sensing and translocation are performed by two distinct conformational states of SNF2h. Such separation of function suggests that these activities could be independently regulated to affect remodeling outcomes.

Cited by (0)