FIG. 4.
ExsA inhibits lateral flagellar gene expression and swarming motility. (A) ExsA affects laf::lux expression. The lateral flagellar gene reporter fusion strain LM5738 (laf::lux) carrying the vector or the IPTG-inducible exsA clone was grown on HI gentamicin plates with 1 mM IPTG and harvested periodically to measure luminescence, which is reported as SLU. Error bars represent standard deviations for triplicate light measurements from each sample. Light values for these strains were significantly different from each other at 5 to 7 h (P < 0.001). A representative experiment of three is shown. (B) ExsA affects swarming. Wild-type (WT) LM5674 or T3SS1 mutant strain LM7035 (ΔVP1672::Camr) carrying the vector or an IPTG-inducible exsA expression construct was spotted on HI gentamicin swarm plates with IPTG and incubated overnight.