Disruption of the spermidine transporter by deleting <i>spuE</i> led to repressed expression of <i>miaB</i> and T3SS genes.

(A) Expression of spuE and miaB in the strains of ΔmiaB and Δvfr relative to that in the wild-type PAO1 strain was measured by RT-qPCR, respectively. (B) β-galactosidase activity of the PexsCEBA-lacZ transcriptional fusion in the wide-type PAO1 strain, ΔspuE, and ΔspuE with in trans expression of miaB. (C) Productions of the intracellular ExsA and extracellular ExoS proteins measured by western blot in the wide-type PAO1 strain, ΔspuE, and ΔspuE with in trans expression of miaB. (D) β-galactosidase activity of the PexsCEBA-lacZ transcriptional fusion in the wide-type PAO1, ΔmiaB, ΔspuE, and ΔmiaBΔspuE strains. (E) Productions of the intracellular ExsA and extracellular ExoS proteins measured by western blot in the wide-type PAO1, ΔmiaB, ΔspuE, and ΔmiaBΔspuE strains. ns, not significant; **, P P t test.