Figure 1.

Forward mutation assay with M13 mp18. The location of PCR primers is indicated by hatched lines. After amplification, denatured and reannealed PCR products were hydrolyzed with MutHLS proteins and/or DraIII and BglII, and the DNA fragment corresponding to the full-length DraIII/BglII product was isolated by size (see Materials and Methods). This product was cloned into an M13 mp18 derivative from which the DraIII/BglII fragment had been removed. In the orientation shown, the DraIII site is 256 bp clockwise from the nearest end of the PCR product while the BglII site is 134 bp counterclockwise from the other end.