Molecular insights into how the motions of the β-barrel and POTRA domains of BamA are coupled for efficient function
The β-barrel assembly machinery (BAM) inserts β-barrel proteins into the outer membrane of Gram-negative bacteria, forming an essential permeability barrier. The core BAM component, BamA, is a β-barrel protein with an N-terminal periplasmic extension comprising five polypeptide transport-associated (POTRA) domains. Whilst BamA's structure is well characterised, it remains unclear how β-barrel and POTRA domain motions are coordinated. Using BamA variants with mutations in the hinge region between these two domains, we demonstrate that hinge flexibility is required for BAM function. Cryo-electron microscopy suggests that hinge rigidity impairs function by structurally decoupling these domains. A screen for spontaneous suppressors identified a mutation at position T434 in an extracellular loop of BamA, which has been previously shown to suppress BAM defects. Studying this variant provides insights into its function as a general rescue mechanism. Our findings underscore how BamA's sequence has been evolutionarily optimised for efficient function.
Authors
- Monika Olejnik
- Jonathan Machin (ORCID: https://orcid.org/0000-0002-1920-149X)
- Raquel Rodríguez-Alonso (ORCID: https://orcid.org/0000-0001-5548-6819)
- Neil A. Ranson (ORCID: https://orcid.org/0000-0002-3640-5275)
- Naemi Csoma (ORCID: https://orcid.org/0000-0002-2858-5771)
- Bogdan Iuliu Iorga (ORCID: https://orcid.org/0000-0003-0392-1350)
- Seung-Hyun Cho (ORCID: https://orcid.org/0000-0002-5548-4239)
- Antonio N. Calabrese (ORCID: https://orcid.org/0000-0003-2437-7761)
- James Whitehouse (ORCID: https://orcid.org/0000-0003-0088-4312)
- Till F. Schäberle (ORCID: https://orcid.org/0000-0001-9947-8079)
- Sheena E. Radford (ORCID: https://orcid.org/0000-0002-3079-8039)
- Jean‐François Collet
- Adam Cahill
Institutions
- Institut de Chimie des Substances Naturelles (FR)
- University of Leeds (GB)
- Justus-Liebig-Universität Gießen (DE)
- Université Paris-Saclay (FR)
- de Duve Institute (BE)
- German Center for Infection Research (DE)
- Fraunhofer Institute for Molecular Biology and Applied Ecology (DE)
- Walloon Excellence in Lifesciences and Biotechnology (BE)
- Institute of Structural and Molecular Biology (GB)
- UCLouvain (BE)
Publication Details
- Journal
- Nature Communications
- Published
- 2025-10-03
- DOI
- https://doi.org/10.1038/s41467-025-63897-y
- Citations
- 1
- Primary Topic
- Bacterial Genetics and Biotechnology
- Type
- article
- Field-Weighted Citation Impact
- 1.82
Funders
- Deutsches Zentrum für Infektionsforschung
- University of Leeds
- European Commission
- Agence Nationale de la Recherche
- Bundesministerium für Bildung und Forschung
- Fonds De La Recherche Scientifique - FNRS
- Fédération Wallonie-Bruxelles
- Rikkyo University
- Walloon excellence in life sciences and biotechnology
- National Institutes of Health
- University of California, San Francisco
- Medical Research Council
- Engineering and Physical Sciences Research Council
- Biotechnology and Biological Sciences Research Council