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Enzymatic methylation of chemically alkylated DNA and poly(dG-dC).poly(dG-dC) in B and Z forms

1983; Elsevier BV; Volume: 116; Issue: 2 Linguagem: Inglês

10.1016/0006-291x(83)90579-x

1090-2104

Annie Pfohl‐Leszkowicz, Serge Boiteux, Jacques Laval, Gérard Keith, G. Dirheimer,

Biopolymer Synthesis and Applications

The enzymatic methylation of chemically alkylated DNA and of poly(dG-dC) X poly(dG-dC) by beef brain DNA(cytosine-5-)-methyltransferase have been tested. The alkylation by dimethylsulfate, which yields mostly 7 methylguanine (m7G) and 3 methyladenine (m3A) do not affect the enzymatic methylation. The dimethylsulfate alkylated poly(dG-dC) X poly(dG-dC) converted into the Z-form in the presence of MgCl2, is just as well methylated as the native or the alkylated polynucleotide in the B-form. The alkylation of DNA or of poly(dG-dC) X poly(dG-dC) by methylnitrosourea yields, in addition to the above base modifications described for dimethylsulfate, methylphosphotriesters and O6-methylguanine. The enzymatic methylation of these substrates modified by methylnitrosourea is decreased. This decrease is proportional to the extent of the chemical alkylation of the substrate.