Fig. 2
Chemotaxis of E. coli is inhibited by the expression of Ppr or Pph. a The chemotactic wild type strain E. coli MM500 was transformed with the plasmids pBAD-Ppr (lanes 1 and 2), pBAD-Pph (lanes 3 and 4) and pBAD-Pph H670A (lanes 5 and 6). Cells were grown in TB medium to an OD600 = 0.5, 0.2% fructose (lanes 1, 3 and 5) or 0.2% arabinose (lanes 2, 4 and 6) was added, and growth was continued for 3 h. Protein expression was analyzed by SDS-PAGE and Coomassie blue staining. The positions of molecular weight markers are indicated. b TB swarm agar plates containing either 0.2% arabinose (upper panels) or 0.2% fructose (lower panels) were inoculated with E. coli MM500 cells bearing the plasmids pBAD-Ppr, pBAD-Pph and pBAD-Pph H670A, pBAD (vector without insert) or pBAD-KdpE. To develop chemotactic rings the plates were incubated for 6 h at 37 °C