9PXG

Cryo-EM structure of apo BAM from P. aeruginosa PAO1

Summary for 9PXG

• Entry DOI: 10.2210/pdb9pxg/pdb
• EMDB information: 71969
• Descriptor: Outer membrane protein assembly factor BamA, Outer membrane protein assembly factor BamB, Outer membrane protein assembly factor BamC, ... (6 entities in total)
• Functional Keywords: protein complex, outer membrane, beta-barrel, protein folding, gram-negative bacterial protein, membrane protein
• Biological source: Pseudomonas aeruginosa PAO1; More
• Total number of polymer chains: 5
• Total formula weight: 233891.56

Authors

Munder, F.,Venugopal, H.,Grinter, R. (deposition date: 2025-08-05, release date: 2026-06-10, Last modification date: 2026-07-15)

Primary citation

Munder, F.,Johnson, M.D.,Samuels, I.,McCaughey, L.,Zdorevskyi, O.,Wang, C.,Kropp, A.,Zavan, L.,Price, E.P.,Sarovich, D.S.,Varshney, S.,McDevitt, C.A.,Venugopal, H.,Sharma, V.,Doyle, M.T.,Short, F.,Ghosal, D.,Connolly, J.P.R.,Knott, G.J.,Grinter, R.
L-type pyocins inhibit the BAM complex to kill without cell entry.
Nat Commun, 2026

PubMed Abstract: Many antibiotics are ineffective against the Gram-negative pathogen Pseudomonas aeruginosa because of intrinsic defence mechanisms, such as the impermeable bacterial outer membrane. Here, we show that protein antibiotics called L-type pyocins kill P. aeruginosa by inhibiting the β-barrel assembly machinery (BAM) complex at the cell surface, halting outer-membrane protein assembly. Using single-particle cryo-electron microscopy, we show that L-type pyocins bind a surface-exposed region of BamA and deploy a C-terminal peptide that competitively inhibits the BAM complex, demonstrating that cell entry is not required for antibiotic activity. We combine genetics, multi-omics and cryo-electron tomography to show that BAM complex inhibition by L-type pyocins or the cyclic-peptide antibiotic, darobactin, triggers a multifaceted transcriptomic, proteomic, and morphological response. BAM inhibition ultimately leads to a catastrophic loss of membrane integrity and cell death. These results validate BAM as a target for antibiotics that do not enter the cell and define an engineerable system for their development.

PubMed: 42393045
DOI: 10.1038/s41467-026-74995-w

Experimental method

ELECTRON MICROSCOPY (2.75 Å)