Fig. 5.

Ssp6 intoxication affects the outer membrane. a Visualisation of cells of E. coli MG1655 carrying empty vector control (VC, pBAD18-Kn) or plasmids directing the expression of Ssp6 fused with an N-terminal OmpA signal peptide (sp-Ssp6), either alone or with Sip6, using the membrane stain FM4-64 and fluorescence microscopy. FM4-64 staining was performed following growth in liquid LB containing 0.2% l-arabinose. Panels show DIC image (left) and FM4-64 channel (right). Scale bar 2 μm. Images are representative of four independent experiments. b Measurement of NPN uptake by E. coli expressing sp-Ssp6 alone or with Sip6, as in part a. NPN accumulation is expressed as arbitrary fluorescence units (AU) and bars show mean +/− SEM, with individual data points superimposed (n = 3 independent experiments; ****p < 0.0001, one-way ANOVA with Dunnett’s test). Source data are provided as a Source Data file.