[Molecular mechanisms of nucleic acid biosynthesis errors induced by alkylation of the nitrogen bases]

The possible pathways of nucleic acid synthesis errors induced by alkylation of the nitrogen bases are considered. Using the atom-atom potential method, intermolecular interaction energy is calculated for coplanar pairs containing a normal base and N- or O-methylated analogue. By analysing the calculation results in terms of the conception of recognition centers of template enzymes the base pairs, which may occur in nucleic acid biosynthesis, were found. The preferential arising of G : C leads to A : T transitions is explained by formation of m6G : T pair. m6G : A and methylated pyrimidine : pyrimidine pair formation is supposed to be the pathways of transversions. All the data available concerning DNA and RNA synthesis on templates containing methylated analogues are explained by formation of wobble-pairs, pairs with one of the nucleotides in syn-conformation and pairs with one H-bond and a short C--H ... O or C--H ... N contact.