Browse by author
Lookup NU author(s): Dr Augustinas SilaleORCiD, Professor Bert van den BergORCiD
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
© The Author(s) 2025. Outer membrane proteins (OMPs) define the surface biology of Gram-negative bacteria, with roles in adhesion, transport, catalysis and signalling. Specifically, porin beta-barrels are common diffusion channels, predominantly monomeric/trimeric in nature. Here we show that the major OMP of the bacterial predator Bdellovibrio bacteriovorus, PopA, differs from this architecture, forming a pentameric porin-like superstructure. Our X-ray and cryo-EM structures reveal a bowl-shape composite outer β-wall, which houses a central chamber that encloses a section of the lipid bilayer. We demonstrate that PopA, reported to insert into prey inner membrane, causes defects when directed into Escherichia coli membranes. We discover widespread PopA homologues, including likely tetramers and hexamers, that retain the lipid chamber; a similar chamber is formed by an unrelated smaller closed-barrel family, implicating this as a general feature. Our work thus defines oligomeric OMP superfamilies, whose deviation from prior structures requires us to revisit existing membrane-interaction motifs and folding models.
Author(s): Parr RJ, Santin YG, Ratkeviciute G, Caulton SG, Radford P, Gurvic D, Jenkins M, Doyle MT, Mead L, Silale A, van den Berg B, Knowles TJ, Sockett RE, Stansfeld PJ, Laloux G, Lovering AL
Publication type: Article
Publication status: Published
Journal: Nature Communications
Year: 2025
Volume: 16
Online publication date: 05/07/2025
Acceptance date: 27/06/2025
Date deposited: 21/07/2025
ISSN (electronic): 2041-1723
Publisher: Springer Nature
URL: https://doi.org/10.1038/s41467-025-61633-0
DOI: 10.1038/s41467-025-61633-0
Data Access Statement: Atomic coordinates have been deposited in with accession codes 9GA1 (x-ray structure), and 9GF0 and EMD-51308 for the cryoEM structure. Molecular dynamics input, output and parameter files are available at https://doi.org/10.5281/zenodo.15696220. Deposited models for each of the homologues are available at ModelArchive (modelarchive.org) with the accession codes ma-n3ds4 (IPM56_03505 hexamer), ma e64a6 (C0V70_02135 pentamer), ma-uceig (C0V70_02140 pentamer), ma-rkx5z (Tde_2508 hexamer), ma-lgpuq (Hore_23180 tetramer), mac773r (Bt_1926 pentamer), ma-zp266 (HMPREF9455_00941 tetramer) and ma-czwi5 (CHU_0007 hexamer). Source data are provided as Source Data files. Source data are provided with this paper.
Altmetrics provided by Altmetric
