Fig. 5. Probing the interactions between BamA POTRA5 and turn 4.

a Zoomed view of the interaction between POTRA5 and turn 4 (T4) in the outward open state (dashed box from Fig. 3a, left panel), with four putative ‘lock’ residues shown in stick. b JCM166 cells were transformed with each of the indicated plasmids and serially diluted and spotted onto LB-agar plates with the indicated conditions. Each was performed at least in triplicate with representative images shown. c Zoomed view of the interaction between POTRA5 and turn 4 (T4), with the location of the two crosslink pairs indicated by yellow (393/584) and pink (396/583) spheres. d Plate assay using JCM166 cells transformed with each crosslink mutant and plated onto LB agar plates with and without arabinose. Each was performed at least in triplicate with representative images shown. e Analysis of the crosslink mutants by western blot on a 5% SDS-PAGE gel showing the direct observation of the crosslinked species (ox), which can be reduced (red) in the presence of DTT. Assays were performed at least in triplicate with a representative image shown. Source data are provided as a Source Data file. f JCM166 cells were transformed with each of the crosslink mutants and serially diluted and spotted onto LB-agar plates with the indicated conditions. The crosslink mutants were challenged with the antibiotics vancomycin (vanco) and rifampicin (rif) to identify any subtle changes in the outer membrane integrity. Each was performed at least in triplicate with representative images shown.