H3K9me3 modified histone binding

Definition

Target type: molecularfunction

Binding to a histone H3 in which the lysine residue at position 9 has been modified by trimethylation. [PMID:30110338]

H3K9me3 is a histone modification that plays a crucial role in regulating gene expression, primarily through its association with heterochromatin formation and transcriptional silencing. The tri-methylation of lysine 9 on histone H3 (H3K9me3) serves as a binding site for a specific class of proteins known as chromodomain proteins. These proteins contain a conserved chromodomain that recognizes and binds to the methylated lysine residue.

The binding of chromodomain proteins to H3K9me3 initiates a cascade of events that ultimately leads to the formation of heterochromatin. Heterochromatin is a tightly packed, transcriptionally inactive form of chromatin characterized by its dense structure and the absence of active genes.

The molecular function of H3K9me3 modified histone binding can be summarized as follows:

1. **Chromatin Compaction:** Chromodomain proteins bound to H3K9me3 recruit other chromatin-modifying enzymes, such as histone deacetylases (HDACs), which remove acetyl groups from histone tails. Deacetylation of histones further compacts chromatin, making it inaccessible to transcription factors and RNA polymerase.
2. **Recruitment of Heterochromatin Proteins:** H3K9me3 binding also attracts other proteins involved in heterochromatin formation, including HP1 proteins (heterochromatin protein 1). HP1 proteins bind to H3K9me3 and interact with each other, promoting the spreading of heterochromatin along the chromosome.
3. **Silencing Gene Expression:** The formation of heterochromatin effectively silences gene expression within the region. This silencing is achieved by preventing the binding of transcription factors and RNA polymerase to the DNA, thus inhibiting the initiation of transcription.

In summary, H3K9me3 modified histone binding serves as a molecular "bookmark" that attracts specific proteins, leading to chromatin compaction, heterochromatin formation, and ultimately, transcriptional silencing. This intricate molecular mechanism plays a vital role in regulating gene expression and maintaining genome stability.'
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Proteins (2)

Compounds (18)