Self-quorum quenching regulates flagellar genes expression.

<p>(<b>A</b>) The relative abundance of <i>fliF</i>, <i>flgE</i>, <i>flbT</i>, and <i>fliC</i> mRNAs was determined by qRT-PCR on RNA isolated from bacteria harvested at the early exponential growth phase in 2YT supplemented or not with exogenous C12-HSL (5 µM). Deletion of <i>aibP</i> and addition of exogenous C12-HSL on <i>B. melitensis</i> both result in significant downregulation of the expression of the tested genes (P<0.001 in Student’s t test). ▵<i>aibP PaibP</i> (right panel) is the complemented strain. Results are representative of two independent experiments. Error bars represent standard deviation from biological triplicates. (<b>B</b>) (Left panel) Western Blot analysis of FliC and FlgE production performed on whole protein lysates of bacteria harvested at the early log phase of growth in 2YT. ▵<i>aibP PaibP</i> is the complemented strain. (Right panel) Bacteria were harvested at the early log phase of growth in 2YT in the absence (–) or in the presence of C12-HSL. The FliC and FlgE proteins were detected at their expected size (29 kDa and 41 kDa respectively). Detection of the PrlR or Omp89 was used to normalize total protein content.