Inhibition of fleQ by AlgT is sufficient for the loss of flagellum expression. (A) Western blot of whole-cell lysates. Lane 1, type B flagellin; lane 2, FRD1; lane 3, FRD2700 (FRD1 with fleQ under the control of an arabinose-inducible promoter) with no arabinose; lanes 4 to 7, FRD2700 plus arabinose (lane 4, 0.1% arabinose; lane 5, 0.5% arabinose; lane 6, 1.0% arabinose; lane 7, 2.5% arabinose). (B) Motility assay on 0.3% agar. (I) PAO1 (motile control); (II) FRD1 (nonmotile control); (III) FRD2700 with no arabinose; (IV) FRD2700 plus 0.1% arabinose. (C) TEM of negatively stained P. aeruginosa. (I) FRD2700 with no arabinose; (II) FRD2700 plus 0.1% arabinose; (IV) FRD2700 plus 2.5% arabinose.