ジャーナル: Nat Commun / 年: 2025 タイトル: A porin-like protein used by bacterial predators defines a wider lipid-trapping superfamily. 著者: Rebecca J Parr / Yoann G Santin / Giedrė Ratkevičiūte / Simon G Caulton / Paul Radford / Dominik Gurvič / Matthew Jenkins / Matthew T Doyle / Liam Mead / Augustinas Silale / Bert van den ...著者: Rebecca J Parr / Yoann G Santin / Giedrė Ratkevičiūte / Simon G Caulton / Paul Radford / Dominik Gurvič / Matthew Jenkins / Matthew T Doyle / Liam Mead / Augustinas Silale / Bert van den Berg / Timothy J Knowles / R Elizabeth Sockett / Phillip J Stansfeld / Géraldine Laloux / Andrew L Lovering / 要旨: 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 ...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.
A: Major outer membrane protein B: Major outer membrane protein C: Major outer membrane protein D: Major outer membrane protein E: Major outer membrane protein ヘテロ分子