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Open data
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Basic information
Entry | Database: EMDB / ID: EMD-3135 | |||||||||
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Title | Electron cryo-microscopy of an immune pore | |||||||||
![]() | Reconstruction of the barrel of the membrane attack complex | |||||||||
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![]() | cryo-EM / single particles / membrane protein | |||||||||
Biological species | ![]() | |||||||||
Method | single particle reconstruction / cryo EM / Resolution: 7.3 Å | |||||||||
![]() | Serna M / Bubeck D | |||||||||
![]() | ![]() Title: Structural basis of complement membrane attack complex formation. Authors: Marina Serna / Joanna L Giles / B Paul Morgan / Doryen Bubeck / ![]() Abstract: In response to complement activation, the membrane attack complex (MAC) assembles from fluid-phase proteins to form pores in lipid bilayers. MAC directly lyses pathogens by a 'multi-hit' mechanism; ...In response to complement activation, the membrane attack complex (MAC) assembles from fluid-phase proteins to form pores in lipid bilayers. MAC directly lyses pathogens by a 'multi-hit' mechanism; however, sublytic MAC pores on host cells activate signalling pathways. Previous studies have described the structures of individual MAC components and subcomplexes; however, the molecular details of its assembly and mechanism of action remain unresolved. Here we report the electron cryo-microscopy structure of human MAC at subnanometre resolution. Structural analyses define the stoichiometry of the complete pore and identify a network of interaction interfaces that determine its assembly mechanism. MAC adopts a 'split-washer' configuration, in contrast to the predicted closed ring observed for perforin and cholesterol-dependent cytolysins. Assembly precursors partially penetrate the lipid bilayer, resulting in an irregular β-barrel pore. Our results demonstrate how differences in symmetric and asymmetric components of the MAC underpin a molecular basis for pore formation and suggest a mechanism of action that extends beyond membrane penetration. | |||||||||
History |
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Structure visualization
Movie |
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Structure viewer | EM map: ![]() ![]() ![]() |
Supplemental images |
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Downloads & links
-EMDB archive
Map data | ![]() | 20.4 MB | ![]() | |
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Header (meta data) | ![]() ![]() | 12.6 KB 12.6 KB | Display Display | ![]() |
Images | ![]() | 409.4 KB | ||
Archive directory | ![]() ![]() | HTTPS FTP |
-Related structure data
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Links
EMDB pages | ![]() ![]() |
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Map
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Annotation | Reconstruction of the barrel of the membrane attack complex | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Voxel size | X=Y=Z: 1.4 Å | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Density |
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Symmetry | Space group: 1 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Details | EMDB XML:
CCP4 map header:
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-Supplemental data
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Sample components
-Entire : Membrane attack complex
Entire | Name: Membrane attack complex |
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Components |
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-Supramolecule #1000: Membrane attack complex
Supramolecule | Name: Membrane attack complex / type: sample / ID: 1000 Details: Protein complex was assembled on liposomes and detergent solubilized Number unique components: 7 |
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Molecular weight | Theoretical: 1.8 MDa |
-Macromolecule #1: C5
Macromolecule | Name: C5 / type: protein_or_peptide / ID: 1 / Number of copies: 1 / Oligomeric state: monomer / Recombinant expression: No |
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Source (natural) | Organism: ![]() |
Molecular weight | Theoretical: 190 KDa |
-Macromolecule #2: C6
Macromolecule | Name: C6 / type: protein_or_peptide / ID: 2 / Number of copies: 1 / Oligomeric state: monomer / Recombinant expression: No |
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Source (natural) | Organism: ![]() |
Molecular weight | Theoretical: 120 KDa |
-Macromolecule #3: C7
Macromolecule | Name: C7 / type: protein_or_peptide / ID: 3 / Number of copies: 1 / Oligomeric state: monomer / Recombinant expression: No |
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Source (natural) | Organism: ![]() |
Molecular weight | Theoretical: 110 KDa |
-Macromolecule #4: C8 alpha
Macromolecule | Name: C8 alpha / type: protein_or_peptide / ID: 4 / Number of copies: 1 / Oligomeric state: monomer / Recombinant expression: No |
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Source (natural) | Organism: ![]() |
Molecular weight | Theoretical: 152 KDa |
-Macromolecule #5: C8 beta
Macromolecule | Name: C8 beta / type: protein_or_peptide / ID: 5 / Number of copies: 1 / Oligomeric state: monomer / Recombinant expression: No |
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Source (natural) | Organism: ![]() |
Molecular weight | Theoretical: 152 KDa |
-Macromolecule #6: C8 gamma
Macromolecule | Name: C8 gamma / type: protein_or_peptide / ID: 6 / Number of copies: 1 / Oligomeric state: monomer / Recombinant expression: No |
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Source (natural) | Organism: ![]() |
Molecular weight | Theoretical: 152 KDa |
-Macromolecule #7: C9
Macromolecule | Name: C9 / type: protein_or_peptide / ID: 7 / Number of copies: 18 / Oligomeric state: eighteen-mer / Recombinant expression: No |
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Source (natural) | Organism: ![]() |
Molecular weight | Theoretical: 69 KDa |
-Experimental details
-Structure determination
Method | cryo EM |
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![]() | single particle reconstruction |
Aggregation state | particle |
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Sample preparation
Buffer | pH: 7.4 / Details: 20 mM HEPES, 150 mM NaCl |
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Grid | Details: 300 mesh quatifol R1.2/1.3 grids with thin carbon film |
Vitrification | Cryogen name: ETHANE / Chamber humidity: 90 % / Instrument: FEI VITROBOT MARK III |
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Electron microscopy
Microscope | FEI TITAN KRIOS |
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Date | Jul 2, 2015 |
Image recording | Category: CCD / Film or detector model: FEI FALCON II (4k x 4k) / Digitization - Sampling interval: 14.0 µm / Number real images: 622 / Average electron dose: 45 e/Å2 |
Electron beam | Acceleration voltage: 300 kV / Electron source: ![]() |
Electron optics | Illumination mode: FLOOD BEAM / Imaging mode: BRIGHT FIELD / Cs: 2.00 mm / Nominal defocus max: 4.0 µm / Nominal defocus min: 2.0 µm / Nominal magnification: 59000 |
Sample stage | Specimen holder model: FEI TITAN KRIOS AUTOGRID HOLDER |
Experimental equipment | ![]() Model: Titan Krios / Image courtesy: FEI Company |
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Image processing
Details | Masked refinement |
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CTF correction | Details: CTFFIND3, phase flip on each particle |
Final reconstruction | Applied symmetry - Point group: C1 (asymmetric) / Algorithm: OTHER / Resolution.type: BY AUTHOR / Resolution: 7.3 Å / Resolution method: OTHER / Software - Name: RELION, EMAN2 / Number images used: 25343 |