Fig. S1. Effect of N-acetyl-glucosamine and sialyl-lactose on SiiE-dependent invasion. MDCK (A, C) or HeLa (B) cells were infected with Salmonella WT (black bars) or siiF mutant (grey bars) strains. Chitosan (Sigma Aldrich), 3′sialyl-lactose sodium salt or 6′ sialyl-lactose sodium salt (Carbosynth) were resuspended at various concentrations in LB. Bacterial strains were subcultured for 3.5 h in LB containing 0.5 to 20 mg ml−1 chitosan, 3′ sialyl-lactose, 6′ sialyl-lactose, or no addition. Subsequently, the cultures were used for infection of MDCK or HeLa cells as described in the main text. No difference was observed if sialyl-lactose was only present in the 3.5 h culture or also in the infection mix added to host to host cells. Cells were pre-treated with various amounts of chitosan (A, B), 3′ sialyl-lactose (3′ SL) or 6′ sialyl-lactose (6′ SL) (C), or mock treated. Invasion was quantified as described for Fig. 1.

Fig. S2. Binding of various lectins and Salmonella to MDCK cells. MDCK cells were infected with sopE2-deficient Salmonella strain MvP1412 for 5 min. Subsequently, cells were incubated with 12 μg ml−1 of biotinylated WGA, MALII or SNA for further 20 min. Cells were fixed, Salmonella was detected by immunostaining for LPS (green) and lectin binding was detected by TRITC-conjugated Streptavidin (red). Epifluorescence images of the 568 nm emission channel for TRITC heat maps indicating the labelling intensity are shown. Scale bars: 20 μm.

Fig. S3. MDCK cells were infected with sopE2-deficient Salmonella strain MvP1412 for 5 or 15 min, or mock infected. Subsequently, cells were incubated with GST or GST-miniSiiE as indicated and immunostaining for GST/SiiE (green) and Salmonella LPS (red) was performed. Host cell F-actin was labelled with phalloidin-Alexa647 (blue). Scale bar: 20 μm.

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