A porin-like protein used by bacterial predators defines a wider lipid-trapping superfamily

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.

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Publication Details

Journal
Nature Communications
Published
2025-07-05
DOI
https://doi.org/10.1038/s41467-025-61633-0
Citations
2
Primary Topic
Bacterial Genetics and Biotechnology
Type
article
Field-Weighted Citation Impact
3.63

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article

A porin-like protein used by bacterial predators defines a wider lipid-trapping superfamily

Géraldine Laloux, Simon G. Caulton, Rebecca J. Parr, Bert van den Berg et al.
2 citations
Nature Communications
Bacterial Genetics and Biotechnology
3.63
article

A porin-like protein used by bacterial predators defines a wider lipid-trapping superfamily

Géraldine Laloux, Simon G. Caulton, Rebecca J. Parr, Bert van den Berg, Matthew Thomas Doyle, Augustinas Silale, Liam Mead, Paul Radford, Phillip J. Stansfeld, Dominik Gurvič, Giedrė Ratkevičiūtė, Yoann G. Santin, Timothy J. Knowles, R. Elizabeth Sockett, Mark C. Jenkins, Andrew L. Lovering
article en
2 citations

Abstract

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.

Nature CommunicationsVol. 16(1)
The University of Sydney (AU), Australian Synchrotron (AU), University of Warwick (GB), de Duve Institute (BE), Queen's Medical Centre (GB), Walloon Excellence in Lifesciences and Biotechnology (BE), Science Oxford (GB), University of Birmingham (GB), Newcastle University (GB)
Wellcome
Openalex Percentile: Top 7%
Bacterial Genetics and Biotechnology
3.63
DOIOpen Access PDFOpenAlex
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