Answer:
ACETYLATION
Step-by-step explanation:
Chromatin remodeling refers to the changes in the structure of chromatin that allow access to DNA by regulatory proteins, such as transcription factors and RNA polymerase, and thus facilitate gene expression. One of the ways in which chromatin remodeling occurs is through the covalent modification of histone proteins.
Histones are proteins that make up the core of the nucleosome, which is the basic unit of chromatin. They can be modified by the addition or removal of various chemical groups, such as acetyl, methyl, and phosphate groups. Acetylation is one of the most well-studied histone modifications, and it plays a critical role in gene expression.
Acetylation of specific lysine residues on histone tails neutralizes their positive charge, which reduces the interaction between the histones and the negatively charged DNA backbone. This opens up the chromatin structure and allows regulatory proteins to access the DNA, leading to transcriptional activation. The enzymes responsible for histone acetylation are called histone acetyltransferases (HATs), while the enzymes that remove acetyl groups are called histone deacetylases (HDACs).