Rapid spontaneous accessibility of nucleosomal DNA
Related Experiment Video
Updated: Aug 20, 2026

Chromatin Accessibility Profiling in Whole Caenorhabditis elegans L4 Larvae
Published on: April 17, 2026
Gu Li1, Marcia Levitus, Carlos Bustamante
1Department of Biochemistry, Molecular Biology, and Cell Biology, Northwestern University, Evanston, Illinois 60208-3500, USA.
Abstract:
DNA wrapped in nucleosomes is sterically occluded, creating obstacles for proteins that must bind it. How proteins gain access to DNA buried inside nucleosomes is not known. Here we report measurements of the rates of spontaneous nucleosome conformational changes in which a stretch of DNA transiently unwraps off the histone surface, starting from one end of the nucleosome, and then rewraps. The rates are rapid. Nucleosomal DNA remains fully wrapped for only approximately 250 ms before spontaneously unwrapping; unwrapped DNA rewraps within approximately 10-50 ms. Spontaneous unwrapping of nucleosomal DNA allows any protein rapid access even to buried stretches of the DNA. Our results explain how remodeling factors can be recruited to particular nucleosomes on a biologically relevant timescale, and they imply that the major impediment to entry of RNA polymerase into a nucleosome is rewrapping of nucleosomal DNA, not unwrapping.
Related Concept Videos
Nucleosome Remodeling
Nucleosome remodeling complex
Eukaryotic cells have specialized enzymes called ATP-dependent nucleosome remodeling enzymes. These enzymes...
Chromatin Packaging
Chromatin Packaging
The chromatin
In combination with specialized DNA binding protein called Histones, the DNA double helix forms a compact DNA: protein complex called chromatin. The chromatin itself is further compacted into higher-order structures.
The Nucleosome
In a chromosome, DNA is wound twice around a protein complex called a histone octamer core, which consists of 8 histone proteins. This...
The Nucleosome
DNA is wound twice around a protein complex called histone core, that consist of 8 histone proteins. This complex...
DNA Packaging

