5-methyl C (5meC)

FULL NAME: 5-methylcytosine


DESCRIPTION:
5-Methylcytosine is an epigenetic modification formed by the action of DNA methyltransferases. 5-methylcytosine is a methylated form of the DNA base cytosine. When cytosine is methylated, the DNA maintains the same sequence, but the expression of methylated genes can be altered (the study of this is called epigenetics). 5-Methylcytosine is an epigenetic modification formed by the action of DNA methyltransferases. The function of this chemical varies significantly among species: - In bacteria, 5-methylcytosine can be found at a variety of sites, and is often used as a marker to protect DNA from being cut by native methylation-sensitive restriction enzymes. - In plants, 5-methylcytosine occurs at CpG, CpHpG and CpHpH sequences (where H = A, C or T). - In fungi and animals, 5-methylcytosine predominantly occurs at CpG dinucleotides. Most eukaryotes methylate only a small percentage of these sites, but 70-80% of CpG cytosines are methylated in vertebrates. While spontaneous deamination of cytosine forms uracil, which is recognized and removed by DNA repair enzymes, deamination of 5-methylcytosine forms thymine. This conversion of a DNA base from cytosine (C) to thymine (T) can result in a transition mutation. In addition, active enzymatic deamination of cytosine or 5-methylcytosine by the APOBEC family of cytosine deaminases could have beneficial implications on various cellular processes as well as on organismal evolution. The implications of deamination on 5-hydroxymethylcytosine, on the other hand, remains less understood.

DAMAGE TYPE: epigenetic modification (no DAMAGE)


DNA DAMAGE SOURCE(S) (MAIN):
DNA methyltransferase


DNA DAMAGE EFFECT(S) (MAIN):
no mutagenesis


Last modification date: Oct. 10, 2011