A simple and efficient method for the oligonucleotide-directed mutagenesis using plasmid DNA template and phosphorothioate-modified nucleotide.

We have developed a simple and efficient method for oligonucleotide-directed mutagenesis with double-stranded (plasmid) DNA as a template. The template was simply and rapidly prepared by cell lysis and the following DNA denaturation with alkali. The chain elongation was performed with phosphorothioate-modified nucleotide at 37 degrees C. After the selective digestion of original DNA with NciI and exonuclease III, the desired mutated gene was obtained at a high frequency (about 70%).