7BM5

Crystal structure of Fab1, the Fab fragment of the anti-BamA monoclonal antibody MAB1

Summary for 7BM5

• Entry DOI: 10.2210/pdb7bm5/pdb
• Descriptor: Fab1 light chain, Fab1 heavy chain (2 entities in total)
• Functional Keywords: antibody, antibiotic, fab, bama, immune system
• Biological source: Homo sapiens (Human); More
• Total number of polymer chains: 12
• Total formula weight: 288863.29

Authors

White, P.,Storek, K.M.,Rutherford, S.T.,Radford, S.E. (deposition date: 2021-01-19, release date: 2021-06-02, Last modification date: 2024-10-16)

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

X-RAY DIFFRACTION (2.95 Å)