Fig. 4

TleV1 is toxic to both E. coli and V. cholerae cells. a Wild-type and periplasmic Tat-tagged tleV1 genes were expressed in E. coli cells under the control of the pBAD promoter. Cells carrying the effector were then spotted on glucose 0.2% or arabinose 0.2% plates (and antibiotic to maintain the plasmid). b The clinical wild-type C6706 V. cholerae strain was competed with C6706* (a C6706 strain that constitutively expresses QstR and the T6SS apparatus) with an integrated Aux 5a cluster (C6706*:Aux 5a) at its lacZ gene locus. A T6SS⁻ C6706*:Aux 5a mutant and a C6706*:Aux 5a ΔtleV1 mutant were also competed against the WT C6706 target. A one-way ANOVA with post-hoc Tukey HSD test was performed, ****p < 0.0001. c Competitions between WT C6706 vs. C6706*:Aux 5a and WT C6706 vs. C6706*:Aux 5a ΔtleV1 were visualized using propidium iodide (staining red cells with a compromised membrane) as an indicator for cellular lysis. Black scale bars represent 40 μM