Fig. 3: Structural and functional consequences of losing BamP.
From: A new paradigm for outer membrane protein biogenesis in the Bacteroidota
a, Comparison of the structure of the BamAD complex from a BamP-deleted (ΔbamP) background and a BamAP complex from the wild-type (WT) background. The proposed phenylalanine molecule is shown in orange space-filling representation. b, Overlay of the structures shown in a aligned on the N-terminal 100 residues of the BamA barrel. c, Detail from b showing the enlargement and register shift of the sheet between the BamA barrel N and C terminal strands upon BamP removal and the incompatible binding modes of BamP and the putative phenylalanine (orange space-filling representation). Spheres show the Cα atom of Gly897 in each model. d, Cryo-EM volume for the BamAD complex from a BamP-deleted background reveals a partially occupied second barrel (silver). Inset shows the putative phenylalanine density. e, Superposition of the complex in d with an E. coli BamA–EspP complex29 (PDB: 8BO2; yellow) aligning on the blue BamAFj. The view is from the cell exterior but truncated in the periplasm for clarity. A second copy of BamAFj (silver) has been docked into the second barrel density in d and occupies the same position as the EspP substrate (yellow barrel, right). f, Removal of BamP homologues sensitizes F. johnsoniae to darobactin. The ΔporV Δplug background permeabilizes the OM by opening the T9SS translocon channel15. g, BamP overexpression restores darobactin resistance to a strain lacking all BamP homologues. Strains contain plasmids overexpressing Twin-Strep-tagged BamP (pTSBamP) or BamP4 (pTSBamP4). f,g, Similar data were obtained for three biological repeats.
