L-type pyocins inhibit the BAM complex to kill without cell entry
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. L-type pyocins are a class of bacteriocin-like proteins with antibacterial activity. Here, the authors show that these proteins kill the pathogen Pseudomonas aeruginosa by inhibiting the BAM complex at the bacterial cell surface, halting outer-membrane protein assembly.
Authors
- Vivek Sharma (ORCID: https://orcid.org/0000-0002-8838-3151)
- Gavin J. Knott (ORCID: https://orcid.org/0000-0002-9007-6273)
- James P. R. Connolly (ORCID: https://orcid.org/0000-0002-0394-3413)
- Hariprasad Venugopal (ORCID: https://orcid.org/0000-0001-5230-2973)
- Matthew Thomas Doyle (ORCID: https://orcid.org/0000-0002-1876-1209)
- Erin P. Price (ORCID: https://orcid.org/0000-0002-1079-4882)
- Derek S. Sarovich (ORCID: https://orcid.org/0000-0002-6944-3980)
- Francesca L. Short (ORCID: https://orcid.org/0000-0002-0025-4858)
- Ashleigh Kropp (ORCID: https://orcid.org/0000-0002-8027-9050)
- Imogen Samuels (ORCID: https://orcid.org/0009-0009-8861-6590)
- Oleksii Zdorevskyi (ORCID: https://orcid.org/0000-0001-9863-5095)
- Debnath Ghosal (ORCID: https://orcid.org/0000-0002-2227-0330)
- Christopher A. McDevitt (ORCID: https://orcid.org/0000-0003-1596-4841)
- Rhys W. Grinter (ORCID: https://orcid.org/0000-0002-8195-5348)
- Lauren Zavan (ORCID: https://orcid.org/0000-0003-4700-3033)
- Matthew D. Johnson (ORCID: https://orcid.org/0000-0002-0808-3336)
- Chunxiao Wang
- Swati Varshney
- Laura McCaughey
- Fabian Munder (ORCID: https://orcid.org/0009-0005-5327-3138)
Institutions
- The University of Sydney (AU)
- University of Helsinki (FI)
- The University of Melbourne (AU)
- University of the Sunshine Coast (AU)
- Discovery Institute (US)
- Discovery Centre (CA)
- Australian Regenerative Medicine Institute (AU)
- Taronga Conservation Society Australia (AU)
- Wellcome Sanger Institute (GB)
- Sunshine Coast University Hospital (AU)
- Peter Doherty Institute (AU)
- Laboratoire de Biologie Physico-Chimique des Protéines Membranaires (FR)
- Monash University (AU)
- Monash Institute of Medical Research (AU)
- University of Glasgow (GB)
- Newcastle University (GB)
Publication Details
- Journal
- Nature Communications
- Published
- 2026-07-02
- DOI
- https://doi.org/10.1038/s41467-026-74995-w
- Primary Topic
- Cellular transport and secretion
- Type
- article
- Field-Weighted Citation Impact
- 0.00
Funders
- Australian Research Council
- National Health and Medical Research Council