Fluorescence was observed on the Nikon E800 and images were processed using Metamorph. Growth curves Strains were grown overnight in PYE supplemented with appropriate antibiotics and diluted to an OD600 of 0.1 in fresh PYE with no antibiotic. They were allowed to grow for two doublings (to OD600 of ~0.4) and diluted again to an OD600 of 0.05 in 10 ml of PYE. 100 μl of the culture was removed and its OD600 recorded every 30 minutes for 5 hours. Swarm assay Strains were grown overnight in PYE supplemented with appropriate antibiotics, diluted to an

OD600 of 0.1, and allowed to grow for two doublings (to OD600 of ~0.4). All strains were diluted to an equal OD600 and 1 μl of the culture was injected into a 0.3% Agar PYE plate. This was incubated at room temperature for 5–7 days in a humid container. Complementation

Plasmid PX-478 cost pSAL14 [17], carrying a wild-type GSK3326595 molecular weight copy of the ctrA gene, was transformed into YB3558. The resulting strain, YB3559, was assayed for complementation of the phenotypes seen in YB3558. Western analysis To examine levels of CtrA in mixed culture, exponentially growing cells were collected and resuspended to equal OD600 in a final volume of 100 μl in 1X SDS loading buffer (62.5 mM Tris–HCl pH 6.8, 10% v/v glycerol, 2% w/v SDS, 0.05% v/v β-mercaptoethanol, 0.0025% w/v Bromophenol blue). 15 μl of this sample was separated on a 10% SDS-polyacrylamide gel and transferred to a nitrocellulose membrane. The membrane was probed with α-CtrA serum [42] at 1:10,000 dilution. The membrane was then probed with HRP-conjugated goat anti-rabbit secondary antibody (Biorad) at 1:20,000, developed using Supersignal Pico (Pierce) and check details imaged on a Kodak imagestation 440CF. For quantification of CtrA levels in wild-type and mutant

strains, four replicates of each sample were loaded on one gel and treated as described above. Once exposed, Kodak Molecular Imaging Software version 4.0.3 was used to quantify the intensity of each band and band intensities were averaged for wild-type and mutant. lacZ fusions of wild-type this website and mutant ctrA promoters The ctrAP2::Mn promoter was PCR amplified using the primers M134UP and M134DN (Table 3), incorporating EcoRI and XbaI restriction sites, respectively. The wild-type promoter was amplified using the primers M134DN and CtrAlacUp (Table 3). The digested fragments containing the promoter regions were cloned into the lacZ containing plasmid pLac290 [43]. β-Galactosidase assay Plasmids carrying promoter fusions to lacZ were transferred to YB3558 and CB15 by conjugal mating. The resulting transformants were grown to an OD600 of 0.4 to 0.6 in liquid PYE supplemented with tetracycline. Cells were added to three tubes containing Z-buffer (60 mM sodium phosphate (dibasic), 40 mM sodium phosphate (monobasic), pH 7.0, 10 mM potassium chloride, 1 mM magnesium sulfate, 50 mM β-mercaptoethanol) to a final volume of 800 μl, and 25 μl 0.1% w/v SDS was added.