TABLE 3.

In absence of IPTG required to maintain the resident dnaC plasmid, pAM34dnaC, viability of E. coli KH1061 (ΔdnaC::cat) depends on separate dnaC plasmid

PlasmidRelative plating efficiencya
pACYC184<2 × 10−6
pACYC184dnaC0.95
pINCSSD2.4 × 10−2
pdnaC97 (Pro108Ser)5 × 10−2
pdnaC116 (Leu44Pro)1.5 × 10−2
pdnaC250 (Leu11Gln)2.3 × 10−2
  • a The indicated plasmids were transformed into KH1061 (ΔdnaC::cat) carrying the plasmid pAM34dnaC. Various dilutions of the transformation mixture were plated on LB medium lacking or supplemented with 0.5 mM IPTG and either tetracycline or kanamycin to select for the respective plasmids. Ampicillin was included in the medium containing IPTG to select for colonies carrying pAM34dnaC. Incubation was carried out at 37°C overnight. Relative plating efficiency is the ratio of the number of colonies detected in the absence of IPTG to that in its presence.