DNA methylase from HeLa cell nuclei.
A DNA methylase has been purified 270-fold from HeLa cell nuclei by chromatography on DEAE-cellulose, phosphocellulose, and hydroxyapatite. The enzyme transfers methyl groups from S-adenosyl-L-methionine to cytosine residues in DNA. The sole product of the reaction has been identified as 5-methylcytosine. The enzyme is able to methylate homologous (HeLa) DNA, although to a lesser extent than heterologous DNA. This may be due to incomplete methylation of HeLa DNA synthesized in vivo. The HeLa enzyme can methylate single-stranded DNA, and does so to an extent three times greater than that of the corresponding double-stranded DNA. In single-stranded M. luteus DNA, at least 2.4% of the cytosine residues can be methylated in vitro by the enzyme. The enzyme also can methylate poly (dG-dC-dG-dC) and poly (dG, dC). Bilateral nearest neighbors to the 5-methylcytosine have been determined with M. luteus DNA in vitro and HeLa DNA in vivo. The 5' neighbor can be either G or C while the 3' neighbor is always G and this sequence is, thus, p(G/C)pmCpG.
D002467:Cell Nucleus / Q000032:analysis / Q000201:enzymology*; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000302:isolation & purification / Q000378:metabolism*; D004273:DNA, Neoplasm / Q000032:analysis; D006367:HeLa Cells / Q000032:analysis / Q000201:enzymology*; D007700:Kinetics; D008780:Methyltransferases / Q000378:metabolism*; D013329:Structure-Activity Relationship
D004273:DNA, Neoplasm; D008780:Methyltransferases; D004248:DNA (Cytosine-5-)-Methyltransferases