Methyltransferase

HaeIII methyltransferase / DNA. Rendered from PDB 1DCT.

Methyl-Group

Methylation Sites on DNA

A methyltransferase is a type of transferase enzyme that transfers a methyl group from a donor to an acceptor.

Methylation often occurs on nucleic bases in DNA or amino acids in protein structures. Methytransferases use a reactive methyl group bound to sulfur in S-adenosyl methionine (SAM) as the methyl donor.

DNA methylation is often utilized to silence and regulate genes without changing the original DNA sequence, an example of epigenetic modification. This methylation occurs on cytosine residues. DNA methylation may be necessary for normal growth from embryonic stages in mammals. When mutant embryonic stem cells lacking the murine DNA methyltransferase gene were introduced to a germline of mice, they caused a recessive lethal phenotype.^[1] Methylation may also be linked to cancer development, as methylation of tumor suppressor genes promotes tumorgenesis and metastasis.^[2]

Site-specific methyltransferases have the same DNA target sequences as certain restriction enzymes. Methylation can also serve to protect DNA from enzymatic cleavage, since restriction enzymes are unable to bind and recognize externally modified sequences. This is especially useful in bacterial restriction modification systems that use restriction enzymes to cleave foreign DNA while keeping their own DNA protected by methylation.

Methylation of amino acids in the formation of proteins leads to more diversity of possible amino acids and, therefore, more diversity of function. The methylation reaction occurs on nitrogen atoms either on the N terminus or on the side-chain position of the protein and are usually irreversible.

Examples include:

• DNA methyltransferase
• Histone methyltransferase
• 5-Methyltetrahydrofolate-homocysteine methyltransferase
• O-methyltransferase

References

1. ^ Li, En., Bestor, T., Jaenish, R., "Targeted mutation of the DNA methyltransferase Gene Results in Embryonic Lethality,"Cell (1992), Vol 69, pg915-926.
2. ^ Laird, PW., Jaenisch, R., "DNA Methylation and Cancer,"Human Molecular Genetics (1994), Vol 3, pg1487-1485.

External links

• MeSH Methyltransferases
• 3-D Structure of DNA Methyltransferase
• A novel methyltransferase : the 7SK snRNA Methylphosphate Capping Enzyme as seen on Flintbox

This enzyme-related article is a stub. You can help Wikipedia by expanding it.v · Categories: EC 2.1 Enzyme stubs Wikimedia Foundation. 2010. Игры ⚽ Поможем сделать НИР H. George Frederickson Jahan Salehi Look at other dictionaries: Méthyltransférase — Groupe méthyle Les méthyltransférases sont un groupe d enzymes de la famille des transférases qui, comme leur nom l indique, transfèrent un groupe méthyle d un donneur à un accepteur. Les méthyltransférases forment la sous classe EC 2.1.1 dans la …   Wikipédia en Français Methyltransferase — Methyltransferasen Enzymklassifikation EC, Kategorie …   Deutsch Wikipedia methyltransferase — Any enzyme transferring methyl groups from one compound to another. SYN: demethylase, methylkinase, transmethylase. * * * meth·yl·trans·fer·ase tran(t)s fər .ās, .āz n any of several transferases that promote transfer of a methyl group from one… …   Medical dictionary Methyltransferase — Me|thyl|trans|fe|ra|se; Syn.: Transmethylase, Methylase: Gruppenbez. für ↑ Transferasen, die Methylgruppen von einem Donator oder Cofaktor (z. B. Adenosylmethionin) auf ein bestimmtes Substrat übertragen (↑ Methylierung), z. B. die Catecholamin O …   Universal-Lexikon methyltransferase — Enzyme that transfers a methyl group from S adenosyl methionine to a substrate. Most commonly encountered in bacterial chemotaxis where the methyl accepting chemotaxis proteins (MCPs) become methylated in the course of adaptation …   Dictionary of molecular biology methyltransferase — noun Any enzyme that catalyzes transmethylation …   Wiktionary methyltransferase — ¦ ̷ ̷  ̷ ̷ ¦ ̷ ̷  ̷ ̷ ˌ ̷ ̷ noun Etymology: methyl + transferase : any of several transferases that promote transfer of a methyl group from one compound to another …   Useful english dictionary Acetylserotonin O-methyltransferase — Identifiers EC number 2.1.1.4 CAS number 9029 77 0 …   Wikipedia O-methyltransferase — An O methylated flavonoid (OMT) is a type of methyltransferase enzyme transferring a methyl group on a molecule. Examples are : Acetylserotonin O methyltransferase Apigenin 4 O methyltransferase Caffeate O methyltransferase Caffeoyl CoA O… …   Wikipedia DNA methyltransferase — N 6 DNA Methylase crystal structure of type i restriction enzyme ecoki m protein (ec 2.1.1.72) (m.ecoki) Identifiers Symbol N6 Mtase Pfam …   Wikipedia 18+ © Academic, 2000-2024 Contact us: Technical Support, Advertising Dictionaries export, created on PHP, Joomla, Drupal, WordPress, MODx. Mark and share Search through all dictionaries Translate… Search Internet Share the article and excerpts Direct link … Do a right-click on the link above and select “Copy Link”