Escherichia coli endA deletion strain for use in two-hybrid shuttle vector selection

genes can beselected and identified in this strain. The mutations were generated usingthe one-step inactivation of chromoso-mal genes method developed by Dat-senko and Wanner (5). Bacteria weremaintained on LB agar medium, andthe cultures were grown in LB broth(Unless otherwise stated, all chemicals,media, and antibiotics are from Sigma-Aldrich Research Reagents, Oakville,ON, Canada). SOC broth (6) was usedfor the recovery of bacteria after elec-troporation. Kanamycin- and ampi-cillin-resistant transformants were se-lected on LB plates containing 25µg/mL kanamycin and 100 µg/mLampicillin, respectively. M9 minimalmedium (6) lacking uracil, leucine,tryptophan, or histidine was used to testthe auxotrophic phenotype of putativemutants. A 0.2% (w/v) final concentra-tion of arabinose was used for the in-duction of the red recombinase system(5). PCR primers were produced anddesalted by Canadian Life Technolo-gies (Burlington, ON, Canada). The re-striction enzyme