Inducing expression of lpxA stops growth of the ∆ ripA strain. (A) Terminal OD600 of strains grown in CDM with or without 100 ng ml−1 of anhydrotetracycline (ATc) at 24 hours. LVS, ∆ripA, LVS containing lpxA in trans, and ∆ripA containing lpxA in trans. ATc was used to induce expression of desired genes under the control of the rpsLp-tetR system . (B) Representative growth curve in CDM with induced expression of lpxA or ripA using 100 ng ml−1 of ATc. Terminal OD600 at 24 hours of S102 and S102 with ripA in trans, under the control of the rpsLp-tetR system. Representative growth curve in CDM where ripA expression was induced with 100 ng ml−1 of ATc. The growth curves were repeated at least three times and statistical significance was determined using Student’s t tests. **P < 0.001.