Chromatin remodeling is the enzyme-assisted movement of nucleosome

Nucleosome

Nucleosomes are the basic unit of DNA packaging in eukaryotes, consisting of a segment of DNA wound around a histone protein core. This structure is often compared to thread wrapped around a spool....

s on DNA.

This is performed by chromatin remodeling complexes like SWI/SNF

SWI/SNF

SWI/SNF is a yeast nucleosome remodeling complex composed of several proteins – products of the SWI and SNF genes as well as several other polypeptides...

 (human, yeast), RSC

Chromatin Structure Remodeling (RSC) Complex

RSC is a 17-subunit complex with the capacity to remodel the structure of chromatin. It exhibits a DNA-dependent ATPase activity stimulated by both free and nucleosomal DNA and a capacity to perturb nucleosome structures...

 (yeast) and Imitation SWI

Imitation SWI

The protein ISWI or imitation SWI of drosophila melanogaster, is the first ATPase subunit which has been isolated in the ISWI chromatin remodeling family. This protein presents high level of similarity to the SWI/SNF chromatin remodeling family in the ATPase domain...

 complexes (fly).

At the core of a chromatin remodeling complex is an ATPase

ATPase

ATPases are a class of enzymes that catalyze the decomposition of adenosine triphosphate into adenosine diphosphate and a free phosphate ion. This dephosphorylation reaction releases energy, which the enzyme harnesses to drive other chemical reactions that would not otherwise occur...

 capable of DNA translocation.

By moving nucleosomes, proteins like transcription factor

Transcription factor

In molecular biology and genetics, a transcription factor is a protein that binds to specific DNA sequences, thereby controlling the flow of genetic information from DNA to mRNA...

s can get access to DNA that was previously unavailable, wrapped around nucleosome

Nucleosome

Nucleosomes are the basic unit of DNA packaging in eukaryotes, consisting of a segment of DNA wound around a histone protein core. This structure is often compared to thread wrapped around a spool....

cores.