Fig. 1

a Experimental design. The plasmid pBS2-SDL was digested with a nicking endonuclease. An oligonucleotide containing a DNA lesion was hybridized with gap plasmid and ligated using T4 DNA ligase. Original plasmids in the sample are digested with restriction enzymes, except for DNA lesion bearing plasmids. T5 exonuclease cuts only the linear DNA plasmids digested by EcoNI, and does not work on sealed DNA plasmids containing a DNA lesion. b Covalently closed circular duplex DNA containing a single lesion. Sixty four-basepair oligonucleotides containing a single DNA lesion site within the EcoNI restriction enzyme site, two nicking endonuclease sites and the plasmid pBS2-SDL (2917 bp) are shown diagrammatically