histone H4K20 methyltransferase activity

Definition

Target type: molecularfunction

Catalysis of the reaction: S-adenosyl-L-methionine + histone H4 L-lysine (position 20) = S-adenosyl-L-homocysteine + histone H4 N6-methyl-L-lysine (position 20). This reaction is the addition of a methyl group to the lysine residue at position 20 of the histone H4 protein. [PMID:12086618]

Histone H4K20 methyltransferase activity is a molecular function that refers to the enzymatic ability to catalyze the transfer of a methyl group from a donor molecule, typically S-adenosyl methionine (SAM), to the lysine residue at position 20 (K20) of histone H4. This methylation event occurs within the N-terminal tail of histone H4, a protein that forms the core of nucleosomes, the fundamental building blocks of chromatin.

The methylation of histone H4K20 plays a crucial role in regulating chromatin structure and gene expression. Different levels of methylation at this residue, ranging from mono- to tri-methylation, can have distinct effects on the chromatin landscape.

**Mono-methylation (H4K20me1)** is generally associated with active transcription and is often enriched at promoters and enhancers. This modification is recognized by specific reader proteins that can recruit additional factors to promote gene expression.

**Di-methylation (H4K20me2)** is typically found in regions of heterochromatin, which is characterized by condensed and transcriptionally inactive chromatin. This modification contributes to the establishment and maintenance of heterochromatin structures.

**Tri-methylation (H4K20me3)** is primarily associated with repressive chromatin domains and is involved in silencing gene expression. It is often found at centromeres and other repetitive regions of the genome, where it helps maintain genomic stability.

The precise mechanisms by which H4K20 methylation regulates chromatin structure and gene expression are complex and involve interactions with multiple factors, including other histone modifications, chromatin remodeling enzymes, and transcription factors.

The enzymes responsible for catalyzing histone H4K20 methylation are known as histone H4K20 methyltransferases (HMTs). These enzymes exhibit distinct substrate specificities and cellular roles. For example, the SETD8 enzyme specifically catalyzes H4K20 monomethylation and plays a role in DNA replication and repair. In contrast, the SUV4-20H enzymes catalyze both di- and tri-methylation of H4K20 and are involved in heterochromatin formation and silencing.'
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Proteins (6)

Compounds (7)