Mirror-Image Thymidine Discriminates against Incorporation of Deoxyribonucleotide Triphosphate into DNA and Repairs Itself by DNA Polymerases.

DNA polymerases are known to recognize preferably d-nucleotides over l-nucleotides during DNA synthesis. Here, we report that several general DNA polymerases catalyze polymerization reactions of nucleotides directed by the DNA template containing an l-thymidine (l-T). The results display that the 5'-3' primer extension of natural nucleotides get to the end at chiral modification site with Taq and Phanta Max DNA polymerases, but the primer extension proceeds to the end of the template catalyzed by Deep Vent (exo- ), Vent (exo- ), and Therminator DNA polymerases. Furthermore, templating l-nucleoside displays a lag in the deoxyribonucleotide triphosphate (dNTP) incorporation rates relative to natural template by kinetics analysis, and polymerase chain reactions were inhibited with the DNA template containing two or three consecutive l-Ts. Most interestingly, no single base mutation or mismatch mixture corresponding to the location of l-T in the template was found, which is physiologically significant because they provide a theoretical basis on the involvement of DNA polymerase in the effective repair of l-T that may lead to cytotoxicity.