7NCS

Lateral-open conformation of the lid-locked BAM complex (BamA E435C S665C, BamBDCE) bound by a bactericidal Fab fragment

Summary for 7NCS

• Entry DOI: 10.2210/pdb7ncs/pdb
• Related: 7BM5 7BNQ 7NBX
• EMDB information: 12232 12262 12271
• Descriptor: Outer membrane protein assembly factor BamA, Outer membrane protein assembly factor BamB, Outer membrane protein assembly factor BamC, ... (7 entities in total)
• Functional Keywords: outer membrane protein assembly, beta-barrel, gram negative bacteria, protein foldase, membrane protein
• Biological source: Escherichia coli K-12 ; More
• Total number of polymer chains: 7
• Total formula weight: 258928.06

Authors

Haysom, S.F.,Machin, J.M. (deposition date: 2021-01-29, release date: 2021-06-02, Last modification date: 2024-10-23)

Primary citation

White, P.,Haysom, S.F.,Iadanza, M.G.,Higgins, A.J.,Machin, J.M.,Whitehouse, J.M.,Horne, J.E.,Schiffrin, B.,Carpenter-Platt, C.,Calabrese, A.N.,Storek, K.M.,Rutherford, S.T.,Brockwell, D.J.,Ranson, N.A.,Radford, S.E.
The role of membrane destabilisation and protein dynamics in BAM catalysed OMP folding.
Nat Commun, 12:4174-4174, 2021

PubMed Abstract: The folding of β-barrel outer membrane proteins (OMPs) in Gram-negative bacteria is catalysed by the β-barrel assembly machinery (BAM). How lateral opening in the β-barrel of the major subunit BamA assists in OMP folding, and the contribution of membrane disruption to BAM catalysis remain unresolved. Here, we use an anti-BamA monoclonal antibody fragment (Fab1) and two disulphide-crosslinked BAM variants (lid-locked (LL), and POTRA-5-locked (P5L)) to dissect these roles. Despite being lethal in vivo, we show that all complexes catalyse folding in vitro, albeit less efficiently than wild-type BAM. CryoEM reveals that while Fab1 and BAM-P5L trap an open-barrel state, BAM-LL contains a mixture of closed and contorted, partially-open structures. Finally, all three complexes globally destabilise the lipid bilayer, while BamA does not, revealing that the BAM lipoproteins are required for this function. Together the results provide insights into the role of BAM structure and lipid dynamics in OMP folding.

PubMed: 34234105
DOI: 10.1038/s41467-021-24432-x

Experimental method

ELECTRON MICROSCOPY (7.1 Å)