Outer membrane protein assembly mediated by BAM-SurA complexes

Abstract

The outer membrane is a formidable barrier that protects Gram-negative bacteria against environmental threats. Its integrity requires the correct folding and insertion of outer membrane proteins (OMPs) by the membrane-embedded β-barrel assembly machinery (BAM). Unfolded OMPs are delivered to BAM by the periplasmic chaperone SurA, but how SurA and BAM work together to ensure successful OMP delivery and folding remains unclear. Here, guided by AlphaFold2 models, we use disulphide bond engineering in an attempt to trap SurA in the act of OMP delivery to BAM, and solve cryoEM structures of a series of complexes. The results suggest that SurA binds BAM at its soluble POTRA-1 domain, which may trigger conformational changes in both BAM and SurA that enable transfer of the unfolded OMP to the BAM lateral gate for insertion into the outer membrane. Mutations that disrupt the interaction between BAM and SurA result in outer membrane assembly defects, supporting the key role of SurA in outer membrane biogenesis.

Metadata

Item Type:	Article
Authors/Creators:	Fenn, K.L. https://orcid.org/0000-0003-0638-2241 Horne, J.E. https://orcid.org/0000-0001-5260-2634 Crossley, J.A. https://orcid.org/0000-0002-6656-1578 Böhringer, T. Horne, R.J. Schӓberle, T.F. Calabrese, A.L. https://orcid.org/0000-0003-2437-7761 Radford, S.E. https://orcid.org/0000-0002-3079-8039 Ranson, N.A. https://orcid.org/0000-0002-3640-5275
Copyright, Publisher and Additional Information:	© The Author(s) 2024. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/ licenses/by/4.0/.
Dates:	Published: 1 September 2024 Published (online): 1 September 2024 Accepted: 2 August 2024
Institution:	The University of Leeds
Academic Units:	The University of Leeds > Faculty of Biological Sciences (Leeds) > School of Molecular and Cellular Biology (Leeds) > Cryo EM, Image Processing (Leeds)
Funding Information:	Funder Grant number MRC (Medical Research Council) MR/Y012453/1 BBSRC (Biotechnology & Biological Sciences Research Council) BB/X015653/1 Wellcome Trust 221524/Z/20/Z
Depositing User:	Symplectic Publications
Date Deposited:	16 Aug 2024 08:45
Last Modified:	24 Jan 2025 11:24
Published Version:	https://www.nature.com/articles/s41467-024-51358-x
Status:	Published
Publisher:	Nature Research
Identification Number:	10.1038/s41467-024-51358-x
Related URLs:	Dataset
Open Archives Initiative ID (OAI ID):	oai:eprints.whiterose.ac.uk:216160

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Outer membrane protein assembly mediated by BAM-SurA complexes

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Outer membrane protein assembly mediated by BAM-SurA complexes

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