Figure 1

E. coli chromosomal DNA insert in high copy plasmid clone pAQ5 and its derivatives ( a ) Clone pAQ5 containing sequence in the upp-purM-purN region was selected from an E. coli genomic DNA plasmid library for resistance to cell killing mediated by mutant topoisomerase I YpTOP1-D117N expressed in BW117N. PCR was used to amplify the intergenic sequence shown in (b) for cloning into pCR-TOPO-XL cloning vector in the construction of pInter. The sequence of the FNR and PurR binding site deleted in pInterD1 and pInterD2 is shown in (c).