DNA methyltransferases

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DNA methyltransferases
Enzyme Classifications
EC, category 2.1.1.37 ,  methyltransferases
Response type DNA methylation , transfer of a methyl group to the pyrimidine ring of the cytosine in position 5 by a "DNA (cytosine-5 -) methyltransferase" (EC 2.1.1.37).
Substrate Cytosine within DNA
Products 5-methylcytosine within DNA
EC, category 2.1.1.72 ,  methyltransferases
Response type DNA methylation, transfer of a methyl group to position N 6 ( amino group on the purine ring in position 6) of the adenine by a "site-specific DNA methyltransferase (adenine-specific)" (EC 2.1.1.72).
Substrate Adenine within DNA
Products N 6 -methyladenine within DNA
EC, category 2.1.1.113 ,  methyltransferases
Response type DNA methylation, transfer of a methyl group to position N 4 of the cytosine (to the amino group on the pyrimidine ring in position 4) by a “site-specific DNA methyltransferase (cytosine-N (4) -specific)” (EC 2.1.1.113 ).
Substrate Cytosine within DNA
Products N 4 -methylcytosine within DNA

DNA methyl transferases , also known as DNA MTases, are enzymes that transfer methyl groups to nucleobases in DNA. The DNA methylation catalyzed by these enzymes has a variety of biological functions. In bacteria they are among other things used bacteria's DNA to methylate, so for example, restriction enzymes foreign DNA and own DNA may differ. All known DNA methyl transferases use S-adenosyl methionine (SAM) as a methyl group donor.

Classification

EC classification

According to the classification by EC numbers, the DNA MTases are represented with three entries within the methyl transferases (EC 2.1.1 - ExPASy ), which are defined according to the chemical reactions they catalyze:

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The DNA methyltransferases and the EC classification system.

Within the EC number system, the DNA methyltransferases are not an enzyme class (ENZYME class) and not a single entry (ENZYME entry).

The DNA methyltransferases ( en: DNA methyltransferases ) have three entries (ENZYME entries) within a longer list of methyltransferases ( en: Methyltransferases ; ENZYME class: 2.1.1).

The methyl transferases belong to the enzymes that transfer groups with a carbon atom (transferring one-carbon groups; ENZYME class: 2.1), which in turn belong to the transferases ( en: Transferases ; ENZYME class: 2).

The entries for DNA methylferases are:

  • " DNA (cytosine-5 -) - methyltransferase " (ENZYME entry: EC 2.1.1.37),
  • " Site-specific DNA-methyltransferase (adenine-specific) " (ENZYME entry: EC 2.1.1.72) and
  • " Site-specific DNA-methyltransferase (cytosine-N (4) -specific) " (ENZYME entry: EC 2.1.1.113).

The information with the word "ENZYME" was found on the ExPASy SIB Bioinformatics Resource Portal (accessed October 17, 2019, e.g.).

Classification according to the methylation status of the DNA (maintenance and de novo )

In living beings with pronounced differentiation , the DNA methylases are divided into different stages of development according to their appearance . In plants and animals, differentiation is often associated with extensive changes in the methylation state of the DNA; this was especially true for various model organisms , e.g. B. in the field cress ( Arabidopsis thaliana , representative of the vascular plants ) and in the house mouse ( Mus musculus , representative of the mammals ) examined.

De novo DNA methyltransferases (English " de novo DNA methyltransferases") recognize specific sites in the DNA that allow them to methylate cytosine de novo . In mammals, this is particularly important in the early embryonic development, as it creates a methylation pattern (see also genomic imprinting ).

DNA methyltransferases for "maintenance" add methyl groups to those points in the DNA where a methyl group is already present on a DNA strand. This preserves the methylation pattern that was built up once in the embryonic development by the de novo DNA methyltransferases.

literature

  • WA Loenen, AS Daniel, HD Braymer, NE Murray: Organization and sequence of the hsd genes of Escherichia coli K-12. In: J. Mol. Biol. 198 (2), November 1987, pp. 159-170. doi: 10.1016 / 0022-2836 (87) 90303-2 . PMID 3323532 .
  • KE Narva, JL Van Etten, BE Slatko, JS Benner: The amino acid sequence of the eukaryotic DNA [N6-adenine] methyltransferase, M.CviBIII, has regions of similarity with the prokaryotic isoschizomer M.TaqI and other DNA [N6-adenine ] methyltransferases. In: Genes. 74 (1), December 1988, pp. 253-259. doi: 10.1016 / 0378-1119 (88) 90298-3 . PMID 3248728 .
  • R. Lauster: Evolution of type II DNA methyltransferases. A gene duplication model. In: J. Mol. Biol. 206 (2), March 1989, pp. 313-321. doi: 10.1016 / 0022-2836 (89) 90481-6 . PMID 2541254 .
  • A. Timinskas, V. Butkus, A. Janulaitis: Sequence motifs characteristic for DNA [cytosine-N4] and DNA [adenine-N6] methyltransferases. Classification of all DNA methyltransferases. In: Genes. 157 (1-2), May 1995, pp. 3-11. doi: 10.1016 / 0378-1119 (94) 00783-O . PMID 7607512 .
  • J. Labahn, J. Granzin, G. Schluckebier, DP Robinson, WE Jack, I. Schildkraut, W. Saenger: Three-dimensional structure of the adenine-specific DNA methyltransferase M. Taq I in complex with the cofactor S-adenosylmethionine. In: Proc. Natl. Acad. Sci. USA 91 (23), November 1994, pp. 10957-10961. doi: 10.1073 / pnas.91.23.10957 . PMC 45145 (free full text). PMID 7971991 .
  • JE Kelleher, AS Daniel, NE Murray: Mutations that confer de novo activity upon maintenance methyltransferase. In: Journal of Molecular Biology. 221 (2), 1991, pp. 431-440. doi: 10.1016 / 0022-2836 (91) 80064-2 . PMID 1833555 .
  • J. Pósfai, AS Bhagwat, RJ Roberts: Sequence motifs specific for cytosine methyltransferases. In: Genes. 74 (1), December 1988, pp. 261-265. doi: 10.1016 / 0378-1119 (88) 90299-5 . PMID 3248729 .
  • S. Kumar, X. Cheng, S. Klimasauskas, S. Mi, J. Posfai, RJ Roberts, GG Wilson: The DNA (cytosine-5) methyltransferases. In: Nucleic Acids Res. 22 (1), January 1994, pp. 1-10. doi: 10.1093 / nar / 22.1.1 . PMC 307737 (free full text). PMID 8127644 .
  • R. Lauster, TA Trautner, M. Noyer-Weidner: Cytosine-specific type II DNA methyltransferases. A conserved enzyme core with variable target-recognizing domains. In: J. Mol. Biol. 206 (2), March 1989, pp. 305-312. doi: 10.1016 / 0022-2836 (89) 90480-4 . PMID 2716049 .
  • X. Cheng: DNA modification by methyltransferases. In: Curr. Opin. Struct. Biol. 5 (1), February 1995, pp. 4-10. doi: 10.1016 / 0959-440X (95) 80003-J . PMID 7773746 .

Individual evidence

  1. ↑ a b Enymklasse 2.1.1 (enzyme.expasy.org/EC/2.1.1.-). In: ExPASy SIB Bioinformatics Resource Portal. SIB Swiss Institute of Bioinformatics, accessed on October 17, 2019 (English, Release 16-Oct-19).
  2. ^ Marc W. Schmid, Christian Heichinger, Diana Coman Schmid, Daniela Guthörl, Valeria Gagliardini: Contribution of epigenetic variation to adaptation in Arabidopsis . In: Nature Communications . tape 9 , no. 1 , October 25, 2018, ISSN  2041-1723 , p. 4446 , doi : 10.1038 / s41467-018-06932-5 , PMID 30361538 , PMC 6202389 (free full text).
  3. ↑ Jennifer M. SanMiguel, Marisa S. Bartolomei: DNA methylation dynamics of genomic imprinting in mouse development . In: Biology of Reproduction . tape 99 , no. 1 , July 1, 2018, ISSN  1529-7268 , p. 252-262 , doi : 10.1093 / biolre / ioy036 , PMID 29462489 , PMC 6044325 (free full text).