Simultaneous mutations up to six distal sites using a phosphorylation-free and ligase-free polymerase chain reaction-based mutagenesis.

In this study, we present an efficient phosphorylation-free and ligase-free PCR-based multiple site-directed mutagenesis that allows simultaneous mutations up to six distal sites. This method could be extended to any plasmid DNA that is isolated from dam(+)Escherichia coli strains, and the results showed that the simultaneously mutagenic efficiencies of quadruple mutation and sextuple mutation were up to 80% and 40%, respectively.