FIG. 4.

Western blot analysis using anti-TcpA antibody. V. cholerae wild-type O395 and mutant strains ΔtoxR, toxT_Δpro, and tcpA_Δpro (A); wild-type O395 and mutant strain toxT_Δpro/pMMB66HE or toxT_Δpro/ptoxT (B); and wild-type O395 and mutant strain tcpA_Δpro/pMMB66HE or tcpA_Δpro/ptoxT (C) were grown overnight in LB medium at 30°C. IPTG (1 mM) was added to induce toxT transcription in strains carrying plasmids. ptoxT harbors the toxT ORF on low-copy-number plasmid pMMB66HE under the control of the IPTG-inducible tac promoter. Protein molecular size standards (lane M) are indicated on the left. w.t., wild type.