Unnatural base pairs for specific transcription

An unnatural base pair of 2-amino-6-(N,N-dimethylamino)purine (designated a s x) and pyridin-2-one (designated as y) has been developed for specific tr anscription. The ribonucleoside triphosphates of y and a modified y, 5-meth ylpyridin-2-one, are selectively incorporated into RNA opposite x in the te mplates by T7 RNA polymerase, In addition, the sequences of the DNA templat es containing x can be confirmed by a dideoxynucleotide chain-terminator me thod supplemented with the deoxynucleoside triphosphate of y, The bulky dim ethylamino group of x in the templates effectively eliminates noncognate pa iring with the natural bases. These results enable RNA biosynthesis for the specific incorporation of unnatural nucleotides at the desired positions.