FIG 4.
The ΔcysL mutation activates Spx. (A) Low and high levels of trxA inhibit biofilm formation in the ΔcysL mutant. Pspac-trxA and Pspac-trxA ΔcysL mutants were grown at 30°C for 48 h in 2×SGG with the indicated concentrations of IPTG. (B) Growth profiles of ΔcysL and Δspx mutants. Strains were grown in 2×SGG medium with vigorous shaking. Arrows indicate the time points at which samples were taken for RNA isolation. (C) Northern blot analysis of trxA and trxB. Transcripts were detected with gene-specific digoxigenin (DIG)-labeled RNA probes. Time point numbers correspond to the time points shown in panel B. trxA transcripts from PB and PA promoters are indicated by arrows. rRNA stained with methylene blue is shown as a loading control.