Yeast Chd1p Unwraps the Exit Side DNA upon ATP Binding to Facilitate the Nucleosome Translocation Occurring upon ATP Hydrolysis

A Novel N-terminal Region to Chromodomain in CHD7 is Required for the Efficient Remodeling Activity

Chromodomain-Helicase DNA binding protein 7 (CHD7) is an ATP dependent chromatin remodeler involved in maintaining open chromatin structure. Mutations of CHD7 gene causes multiple developmental disorders, notably CHARGE syndrome. However, there is not much known about the molecular mechanism by which CHD7 remodels nucleosomes. Here, we performed biochemical and biophysical analysis on CHD7 chromatin remodeler and uncover that N-terminal to the Chromodomain (N-CRD) interacts with nucleosome and contains a high conserved arginine stretch, which is reminiscent of arginine anchor. Importantly, this region is required for efficient ATPase stimulation and nucleosome remodeling activity of CHD7. Furthermore, smFRET analysis shows the mutations in the N-CRD causes the defects in remodeling activity. Collectively, our results uncover the functional importance of a previously unidentified N-terminal region in CHD7 and implicate that the multiple domains in chromatin remodelers are involved in regulating their activities.

Multicolor single-molecule FRET for DNA and RNA processes

Single-molecule fluorescence resonance energy transfer (smFRET) is a useful tool for observing the dynamics of protein-nucleic acid interactions. Although most smFRET measurements have used two fluorophores, multicolor smFRET measurements using more than two fluorophores offer more information about how protein-nucleic acid complexes dynamically move, assemble, and disassemble. Multicolor smFRET experiments include three or more fluorophores and at least one donor-acceptor pair. This review highlights how multicolor smFRET is being used to probe the dynamics of three different classes of biochemical processes-protein-DNA interactions, chromatin remodeling, and protein translation.