FIG. 3.
Structure of genes in the origin regions of the strains used in this study. (A) E. coli wild type (Wt). (B) The aadA gene (GenBank accession no. AAC33912) encoding streptomycin adenylyltransferase flanked by transcription and translation termination signals (the ΩSm cassette [66]) is inserted upstream of the E. coli gidA promoter as defined in reference 37. (C) The E. coli oriC was replaced by the oriCIVc region comprising the intergenic region between the V. cholerae mioC and gidA gene homologues and the sequence encoding the first 20 amino acids of the V. cholerae gidA gene homologue in combination with the ΩSm cassette. (D) Same as panel C but with two point mutations. The precise locations of the point mutations are described in the text.