Question

Which histone modifications are bound by Bromodomain containing proteins? Which modifications are bound by Chromodomains? Which are associated with “opening” and which with “closing” of chromatin?

Answer 1

Histone modifications are important in regulating gene expression in eukaryotes. Histone acetylation can directly affect chromatin structure by neutralising charges on the histone tail, and can also function as a binding site for proteins which can directly or indirectly regulate transcription. Bromodomains specifically bind to acetylated lysine residues on histone tails, and bromodomain proteins play an important role in anchoring the complexes. These complexes are a part to acetylated chromatin. Bromodomain proteins are involved in a diverse range of functions, which include acetylating histones, remodeling chromatin, and recruiting other factors necessary for transcription.

The chromodomain is the member of the Royal family. It is found in the HP1/Chromobox and CHD subfamilies of proteins. Chromodomains are histone methylated lysine binders. The functions of these chromodomains can be modulated by additional post-translational modifications or binding to nucleic acids. Thus, Chromodomains are histone methylated-lysine recognition modules that belong to a larger, structurally related family of protein domains, which are referred to as the Royal family.
chromodomain-containing proteins are responsible for aspects of gene regulation related to chromatin remodeling and formation of heterochromatin regions. Thus, chromodomains are useful for closing.
And bromodomains are useful for opening.