Figure 2.

RydC induces cfa expression and activity. (A) Microarray analysis of Salmonella genes affected by pulse overexpression of RydC. RydC expression was induced by addition of arabinose (final concentration: 0.2%) to rydC mutant cells carrying pBAD-RydC or control plasmid pBAD. Changes in transcript abundances were scored on Salmonella-specific microarrays; genes displaying >3-fold change (P-value<0.15) are marked in red. (B) RydC and cfa mRNA levels were determined on northern blots of total RNA extracted from rydC mutant cells carrying plasmids pBAD or pBAD-RydC at indicated time points prior to and after addition of arabinose (Ara). The oligo directed against the 5′ UTR of cfa specifically recognizes cfa1 mRNA. (C) Expression of Cfa-3xFLAG in wild-type and ΔrydC mutant Salmonella either carrying a control construct or a plasmid for the constitutive overexpression of RydC from the P_L promoter was monitored over growth on western blots. (D) Total ion chromatograms of Salmonella wild-type cells carrying a control plasmid or a ΔrydC mutant transformed with the RydC overexpression plasmid pP_LRydC. Cells were grown in M9 minimal medium to exponential phase (OD₆₀₀ of 0.5), and after alkaline hydrolysis, total fatty acids were analysed by LC/MS. Peaks assigned to C₁₆UFA, C₁₇CFA, C₁₈UFA and C₁₉CFA are indicated. (E) Relative quantification of C₁₆UFA, C₁₇CFA, C₁₈UFA and C₁₉CFA in Salmonella Δcfa or ΔrydC carrying either a control plasmid or pP_LRydC. All measurements were normalized to wild type; error bars represent the standard deviation calculated from three independent biological replicates; nd: not detected.

Source data for this figure is available on the online supplementary information page.

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