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Open data
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Basic information
| Entry | Database: PDB / ID: 9h85 | |||||||||
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| Title | BAM-hinge (GSGS) | |||||||||
Components |
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Keywords | MEMBRANE PROTEIN / Outer membrane / folding / OMP | |||||||||
| Function / homology | Function and homology informationBam protein complex / Gram-negative-bacterium-type cell outer membrane assembly / protein insertion into membrane / cell outer membrane / protein-macromolecule adaptor activity / cell adhesion / response to antibiotic / cell surface / identical protein binding / membrane Similarity search - Function | |||||||||
| Biological species | ![]() | |||||||||
| Method | ELECTRON MICROSCOPY / single particle reconstruction / cryo EM / Resolution: 4.2 Å | |||||||||
Authors | Machin, J.M. / Ranson, N.A. | |||||||||
| Funding support | United Kingdom, 2items
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Citation | Journal: Nat Commun / Year: 2025Title: Molecular insights into how the motions of the β-barrel and POTRA domains of BamA are coupled for efficient function. Authors: Naemi Csoma / Jonathan M Machin / James M Whitehouse / Raquel Rodrìguez-Alonso / Monika Olejnik / Adam K Cahill / Seung-Hyun Cho / Till F Schäberle / Bogdan I Iorga / Neil A Ranson / ...Authors: Naemi Csoma / Jonathan M Machin / James M Whitehouse / Raquel Rodrìguez-Alonso / Monika Olejnik / Adam K Cahill / Seung-Hyun Cho / Till F Schäberle / Bogdan I Iorga / Neil A Ranson / Sheena E Radford / Antonio N Calabrese / Jean-François Collet / ![]() Abstract: The β-barrel assembly machinery (BAM) inserts β-barrel proteins into the outer membrane of Gram-negative bacteria, forming an essential permeability barrier. The core BAM component, BamA, is a β- ...The β-barrel assembly machinery (BAM) inserts β-barrel proteins into the outer membrane of Gram-negative bacteria, forming an essential permeability barrier. The core BAM component, BamA, is a β-barrel protein with an N-terminal periplasmic extension comprising five polypeptide transport-associated (POTRA) domains. Whilst BamA's structure is well characterised, it remains unclear how β-barrel and POTRA domain motions are coordinated. Using BamA variants with mutations in the hinge region between these two domains, we demonstrate that hinge flexibility is required for BAM function. Cryo-electron microscopy suggests that hinge rigidity impairs function by structurally decoupling these domains. A screen for spontaneous suppressors identified a mutation at position T434 in an extracellular loop of BamA, which has been previously shown to suppress BAM defects. Studying this variant provides insights into its function as a general rescue mechanism. Our findings underscore how BamA's sequence has been evolutionarily optimised for efficient function. | |||||||||
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Structure visualization
| Structure viewer | Molecule: Molmil Jmol/JSmol |
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Downloads & links
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Download
| PDBx/mmCIF format | 9h85.cif.gz | 476.3 KB | Display | PDBx/mmCIF format |
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| PDB format | pdb9h85.ent.gz | 389.6 KB | Display | PDB format |
| PDBx/mmJSON format | 9h85.json.gz | Tree view | PDBx/mmJSON format | |
| Others | Other downloads |
-Validation report
| Summary document | 9h85_validation.pdf.gz | 1.5 MB | Display | wwPDB validaton report |
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| Full document | 9h85_full_validation.pdf.gz | 1.5 MB | Display | |
| Data in XML | 9h85_validation.xml.gz | 56.4 KB | Display | |
| Data in CIF | 9h85_validation.cif.gz | 83.9 KB | Display | |
| Arichive directory | https://data.pdbj.org/pub/pdb/validation_reports/h8/9h85 ftp://data.pdbj.org/pub/pdb/validation_reports/h8/9h85 | HTTPS FTP |
-Related structure data
| Related structure data | ![]() 51931MC ![]() 9h84C ![]() 9h89C C: citing same article ( M: map data used to model this data |
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| Similar structure data | Similarity search - Function & homology F&H Search |
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Links
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Assembly
| Deposited unit | ![]()
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| 1 |
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Components
| #1: Protein | Mass: 88803.000 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Details: E. coli BamA with GSGS insertion before G410, between the barrel and POTRA domains. Source: (gene. exp.) ![]() ![]() |
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| #2: Protein | Mass: 39882.375 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Details: P77774 / Source: (gene. exp.) ![]() ![]() |
| #3: Protein | Mass: 34401.250 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Source: (gene. exp.) ![]() ![]() |
| #4: Protein | Mass: 25816.818 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Source: (gene. exp.) ![]() ![]() |
| #5: Protein | Mass: 10391.554 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Source: (gene. exp.) ![]() ![]() |
| Has protein modification | N |
-Experimental details
-Experiment
| Experiment | Method: ELECTRON MICROSCOPY |
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| EM experiment | Aggregation state: PARTICLE / 3D reconstruction method: single particle reconstruction |
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Sample preparation
| Component | Name: BAM (beta-barrel assembly machinery) complex with BamA GSGS insertion Type: COMPLEX / Details: Purified as a complex with the insertion / Entity ID: all / Source: RECOMBINANT |
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| Molecular weight | Experimental value: NO |
| Source (natural) | Organism: ![]() |
| Source (recombinant) | Organism: ![]() |
| Buffer solution | pH: 8 |
| Specimen | Conc.: 3.3 mg/ml / Embedding applied: NO / Shadowing applied: NO / Staining applied: NO / Vitrification applied: YES |
| Vitrification | Instrument: FEI VITROBOT MARK IV / Cryogen name: ETHANE / Humidity: 100 % / Chamber temperature: 277 K |
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Electron microscopy imaging
| Experimental equipment | ![]() Model: Titan Krios / Image courtesy: FEI Company |
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| Microscopy | Model: TFS KRIOS |
| Electron gun | Electron source: FIELD EMISSION GUN / Accelerating voltage: 300 kV / Illumination mode: FLOOD BEAM |
| Electron lens | Mode: BRIGHT FIELD / Nominal defocus max: 3000 nm / Nominal defocus min: 900 nm |
| Specimen holder | Cryogen: NITROGEN |
| Image recording | Electron dose: 40 e/Å2 / Film or detector model: FEI FALCON IV (4k x 4k) / Num. of grids imaged: 1 / Num. of real images: 7813 |
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Processing
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| CTF correction | Type: PHASE FLIPPING AND AMPLITUDE CORRECTION | ||||||||||||
| 3D reconstruction | Resolution: 4.2 Å / Resolution method: FSC 0.143 CUT-OFF / Num. of particles: 75557 / Symmetry type: POINT | ||||||||||||
| Atomic model building | Protocol: FLEXIBLE FIT Details: Fitting was done in ISOLDE and the models manually adjusted in coot, coupled with phenix real-space refine minimisation. |
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About Yorodumi






United Kingdom, 2items
Citation






PDBj






FIELD EMISSION GUN