Histone methyltransferase
Encyclopedia
Histone methyltransferases (HMT) are enzyme
s, histone-lysine N-methyltransferase
and histone-arginine N-methyltransferase, that catalyze the transfer of one to three methyl groups from the cofactor
S-Adenosyl methionine
to lysine
and arginine
residues of histone
protein
s. These proteins often contain a SET (Su(var)3-9, Enhancer of Zeste, Trithorax) domain
, however the recently discovered HMT Dot1 lacks the characteristic SET domain.
serves in epigenetic gene regulation. Methylated histones bind DNA more tightly, which inhibits transcription
.
Methylated histones can either repress or activate transcription as different experimental findings suggest. See Histone#Chromatin regulation.
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
s, histone-lysine N-methyltransferase
EZH2
Histone-lysine N-methyltransferase EZH2 is an enzyme that in humans is encoded by the EZH2 gene.This gene encodes a member of the Polycomb-group family. PcG family members form multimeric protein complexes, which are involved in maintaining the transcriptional repressive state of genes over...
and histone-arginine N-methyltransferase, that catalyze the transfer of one to three methyl groups from the cofactor
Cofactor (biochemistry)
A cofactor is a non-protein chemical compound that is bound to a protein and is required for the protein's biological activity. These proteins are commonly enzymes, and cofactors can be considered "helper molecules" that assist in biochemical transformations....
S-Adenosyl methionine
S-Adenosyl methionine
S-Adenosyl methionine is a common cosubstrate involved in methyl group transfers. SAM was first discovered in Italy by G. L. Cantoni in 1952. It is made from adenosine triphosphate and methionine by methionine adenosyltransferase . Transmethylation, transsulfuration, and aminopropylation are the...
to lysine
Lysine
Lysine is an α-amino acid with the chemical formula HO2CCH4NH2. It is an essential amino acid, which means that the human body cannot synthesize it. Its codons are AAA and AAG....
and arginine
Arginine
Arginine is an α-amino acid. The L-form is one of the 20 most common natural amino acids. At the level of molecular genetics, in the structure of the messenger ribonucleic acid mRNA, CGU, CGC, CGA, CGG, AGA, and AGG, are the triplets of nucleotide bases or codons that codify for arginine during...
residues of histone
Histone
In biology, histones are highly alkaline proteins found in eukaryotic cell nuclei that package and order the DNA into structural units called nucleosomes. They are the chief protein components of chromatin, acting as spools around which DNA winds, and play a role in gene regulation...
protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
s. These proteins often contain a SET (Su(var)3-9, Enhancer of Zeste, Trithorax) domain
Protein domain
A protein domain is a part of protein sequence and structure that can evolve, function, and exist independently of the rest of the protein chain. Each domain forms a compact three-dimensional structure and often can be independently stable and folded. Many proteins consist of several structural...
, however the recently discovered HMT Dot1 lacks the characteristic SET domain.
Role in gene regulation
Histone methylationHistone methylation
Histone methylation is the modification of certain amino acids in a histone protein by the addition of one, two, or three methyl groups. In the cell nucleus, DNA is wound around histones...
serves in epigenetic gene regulation. Methylated histones bind DNA more tightly, which inhibits transcription
Transcription (genetics)
Transcription is the process of creating a complementary RNA copy of a sequence of DNA. Both RNA and DNA are nucleic acids, which use base pairs of nucleotides as a complementary language that can be converted back and forth from DNA to RNA by the action of the correct enzymes...
.
Methylated histones can either repress or activate transcription as different experimental findings suggest. See Histone#Chromatin regulation.
See also
- Histone-Modifying EnzymesHistone-Modifying EnzymesThe packaging of the eukaryotic genome into highly condensed chromatin makes it inaccessible to the factors required for gene transcription, DNA replication, recombination and repair. Eukaryotes have developed intricate mechanisms to overcome this repressive barrier imposed by the chromatin...
- Histone acetyltransferaseHistone acetyltransferaseHistone acetyltransferases are enzymes that acetylate conserved lysine amino acids on histone proteins by transferring an acetyl group from acetyl CoA to form ε-N-acetyl lysine....
- Histone deacetylaseHistone deacetylaseHistone deacetylases are a class of enzymes that remove acetyl groups from an ε-N-acetyl lysine amino acid on a histone. This is important because DNA is wrapped around histones, and DNA expression is regulated by acetylation and de-acetylation. Its action is opposite to that of histone...
- RNA polymerase control by chromatin structure
- Histone methylationHistone methylationHistone methylation is the modification of certain amino acids in a histone protein by the addition of one, two, or three methyl groups. In the cell nucleus, DNA is wound around histones...
External links
- GeneReviews/NCBI/NIH/UW entry on Kleefstra Syndrome
- Structure and Function of Histone Methyltransferases. Trievel. 2004
- The Dot1 Histone Methyltransferase and the Rad9 Checkpoint Adaptor Contribute to Cohesin-Dependent Double-Strand Break Repair by Sister Chromatid Recombination in Saccharomyces cerevisiae.