FIG 7 .

An Arg6His substitution in CsrA is sufficient to abolish the response to NRES, even when the Var system is functional. The wild-type strain N16961, the NcsrA.R6H mutant, the vector control strain NcsrA.R6H/pCC1, and the complemented strain NcsrA.R6H/pFCsrA were grown overnight in LB broth and then subcultured 1:100 into T medium with or without 12.5 mM NRES mix. Cells were harvested in mid-log phase, and whole-cell preparations were resolved by SDS-PAGE (10%) and stained by Coomassie blue (A) or immunoblotted using polyclonal anti-ToxR antisera (B).