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The role of membrane destabilisation and protein dynamics in BAM catalysed OMP folding.

<div class='caption-title'>Disulfide-locked BamA variants and Fab1 binding impair BAM-mediated OMP folding in vitro.</div>
<div class='caption-title'>CryoEM resolves two conformations of BAM-LL in detergent.</div>
<div class='caption-title'>Fab1-bound BAM is in a lateral-open conformation.</div>
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
OpenAccess logo Nat Commun 12 4174 (2021)
Related entries: 7bm5, 7bnq, 7nbx, 7ncs

Cited: 8 times
EuropePMC logo PMID: 34234105

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.

Reviews citing this publication (2)

  1. Targeting BAM for Novel Therapeutics against Pathogenic Gram-Negative Bacteria. Overly Cottom C, Stephenson R, Wilson L, Noinaj N. Antibiotics (Basel) 12 679 (2023)
  2. The Love and Hate Relationship between T5SS and Other Secretion Systems in Bacteria. Luo Y, Chen Z, Lian S, Ji X, Zhu C, Zhu G, Xia P. Int J Mol Sci 25 281 (2023)

Articles citing this publication (6)

  1. Small Molecule Antibiotics Inhibit Distinct Stages of Bacterial Outer Membrane Protein Assembly. Peterson JH, Doyle MT, Bernstein HD. mBio 13 e0228622 (2022)
  2. AamA-mediated epigenetic control of genome-wide gene expression and phenotypic traits in Acinetobacter baumannii ATCC 17978. Yang J, Son Y, Kang M, Park W. Microb Genom 9 (2023)
  3. Cryo-EM structures reveal multiple stages of bacterial outer membrane protein folding. Doyle MT, Jimah JR, Dowdy T, Ohlemacher SI, Larion M, Hinshaw JE, Bernstein HD. Cell 185 1143-1156.e13 (2022)
  4. Dynamic interplay between the periplasmic chaperone SurA and the BAM complex in outer membrane protein folding. Schiffrin B, Machin JM, Karamanos TK, Zhuravleva A, Brockwell DJ, Radford SE, Calabrese AN. Commun Biol 5 560 (2022)
  5. Protein-lipid charge interactions control the folding of outer membrane proteins into asymmetric membranes. Machin JM, Kalli AC, Ranson NA, Radford SE. Nat Chem (2023)
  6. Structural basis of BAM-mediated outer membrane β-barrel protein assembly. Shen C, Chang S, Luo Q, Chan KC, Zhang Z, Luo B, Xie T, Lu G, Zhu X, Wei X, Dong C, Zhou R, Zhang X, Tang X, Dong H. Nature 617 185-193 (2023)


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