Figure 1.

The TssL protein is required for Type VI secretion. (A) Effect of the tssL mutation on Hcp protein release. Hcp_HA release was assessed by separating whole cells (WC) and supernatant (Sn) fractions from WT, tssL, or complemented tssL (tssL^WT) cultures. A total of 2 × 10⁸ cells and the TCA-precipitated material of the supernatant from 5 × 10⁸ cells were subjected to 12.5% acrylamide SDS-PAGE and immunodetected using the anti-HA monoclonal antibody (lower panel) and the anti-TolB polyclonal antibodies (lysis control; upper panel). (B) Effect of the tssL mutation on biofilm formation. Biofilms formed in static cultures of WT, tssL or complemented tssL (tssL^WT) cells were visualized on cover glass by crystal violet staining (upper panel) and quantified using the ethanol-solubilization procedure, relative to the WT EAEC strain (lower graph).