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Lateral opening in the intact β-barrel assembly machinery captured by cryo-EM

DOI: 10.1038/ncomms12865 DOI Help

Authors: Matthew G. Iadanza (University of Leeds) , Anna J. Higgins (Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, University of Leeds) , Bob Schiffrin (Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, University of Leeds) , Antonio N. Calabrese (Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, University of Leeds) , David J. Brockwell (Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, University of Leeds) , Alison E. Ashcroft (Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, University of Leeds) , Sheena E. Radford (Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, University of Leeds) , Neil A. Ranson (University of Leeds)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Nature Communications , VOL 7

State: Published (Approved)
Published: September 2016
Diamond Proposal Number(s): 12877 , 13590

Open Access Open Access

Abstract: The β-barrel assembly machinery (BAM) is a ∼203 kDa complex of five proteins (BamA–E), which is essential for viability in E. coli. BAM promotes the folding and insertion of β-barrel proteins into the outer membrane via a poorly understood mechanism. Several current models suggest that BAM functions through a ‘lateral gating’ motion of the β-barrel of BamA. Here we present a cryo-EM structure of the BamABCDE complex, at 4.9 Å resolution. The structure is in a laterally open conformation showing that gating is independent of BamB binding. We describe conformational changes throughout the complex and interactions between BamA, B, D and E, and the detergent micelle that suggest communication between BAM and the lipid bilayer. Finally, using an enhanced reconstitution protocol and functional assays, we show that for the outer membrane protein OmpT, efficient folding in vitro requires lateral gating in BAM.

Subject Areas: Biology and Bio-materials

Diamond Offline Facilities: Electron Bio-Imaging Centre (eBIC)
Instruments: Krios I-Titan Krios I at Diamond

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ncomms12865.pdf

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