7bnq
Lateral-closed conformation of the lid-locked BAM complex (BamA E435C S665C, BamBDCE) by cryoEM
Structural highlights
FunctionBAMA_ECOLI Part of the outer membrane protein assembly complex, which is involved in assembly and insertion of beta-barrel proteins into the outer membrane. Constitutes, with BamD, the core component of the assembly machinery.[1] [2] [3] [4] [5] Publication Abstract from PubMedThe folding of beta-barrel outer membrane proteins (OMPs) in Gram-negative bacteria is catalysed by the beta-barrel assembly machinery (BAM). How lateral opening in the beta-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. The role of membrane destabilisation and protein dynamics in BAM catalysed OMP folding.,White P, Haysom SF, Iadanza MG, Higgins AJ, Machin JM, Whitehouse JM, Horne JE, Schiffrin B, Carpenter-Platt C, Calabrese AN, Storek KM, Rutherford ST, Brockwell DJ, Ranson NA, Radford SE Nat Commun. 2021 Jul 7;12(1):4174. doi: 10.1038/s41467-021-24432-x. PMID:34234105[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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