Extended Data Fig. 1: Surface labelling of BamA using a high-affinity monoclonal antibody.

(A) Growth curves of E. coli BW25113 cells grown in LB with or without the MAB2 Fabs used for live cell labelling showing the Fabs have no effect on bacterial survival. (B) A field of view showing DIC, epifluorescence and 3D-SIM images of BamA labelled using αBamA^AF488 Fabs. Scale bar, 1 μm. (C) BamA labelling by MAB2 is specific for E. coli BamA. BamA and BtuB, used as a control, labelling of the E. coli BW25113 (E. coli sequence) and a strain expressing a modified BamA β-barrel domain (E. coli/K. pneumoniae sequence). Shown are comparative images of cells labelled with αBamA^AF488 or ColE9^AF488. Scale bars, 1 μm. (D) Size distribution of BamA-containing islands demonstrating that the average island diameter is ~150 nm. (E) The density of BamA-containing islands on the surface of exponentially growing E. coli as measured by 3D-SIM (n = 30 cells). (F) Demograph of the fluorescence intensity across the long axis of multiple cells labelled with αBamA^AF488, emphasising the even distribution of BamA molecules in the OM. (G) Integrated localization data from multiple cells showing BamA islands are distributed through the E. coli OM. The analysis is based on the same cells shown in panel F and represents different stages of the cell cycle.