Ambiguous incorporation of N4-aminodeoxycytidine 5'-triphosphate to DNA synthesized in vitro.

Molecular mechanism of the mutation induced by N4-aminocytidine was studied. The specificity of in vitro incorporation of N4-aminodeoxycytidine 5'-triphophate catalyzed by E. coli DNA polymerase large fragment was analyzed. The results have shown that this cytosine analog can be efficiently incorporated as a substitute of cytosine, and that it can also be incorporated with a low efficiency as a substitute of thymine. We have also shown that the N4-aminocytosine incorporated opposite adenine can be excised as its monophosphate at a high frequency. The N4-aminocytosine residues in the polynucleotide templates can be read by the enzyme as efficiently as cytosines, and guanines were incorporated opposite them.