+Open data
-Basic information
Entry | Database: EMDB / ID: EMD-2859 | |||||||||
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Title | 3D Reconstruction of Membrane Protein Complex ExbB4-ExbD1-TonB1 | |||||||||
Map data | ExbB4-ExbD1-TonB1 complex with extensive dimerization between ExbD and TonB periplasmic domains | |||||||||
Sample |
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Keywords | Membrane protein complex / heterodimerization / coordinated rearrangement / iron import | |||||||||
Function / homology | Function and homology information receptor-mediated bacteriophage irreversible attachment to host cell / colicin transport / ferrichrome import into cell / energy transducer activity / bacteriocin transport / cell envelope / cobalamin transport / siderophore transport / intracellular monoatomic cation homeostasis / plasma membrane protein complex ...receptor-mediated bacteriophage irreversible attachment to host cell / colicin transport / ferrichrome import into cell / energy transducer activity / bacteriocin transport / cell envelope / cobalamin transport / siderophore transport / intracellular monoatomic cation homeostasis / plasma membrane protein complex / protein import / transmembrane transporter activity / transmembrane transporter complex / membrane => GO:0016020 / cell outer membrane / transmembrane transport / protein transport / outer membrane-bounded periplasmic space / intracellular iron ion homeostasis / protein stabilization / protein domain specific binding / protein homodimerization activity / identical protein binding / membrane / plasma membrane Similarity search - Function | |||||||||
Biological species | Escherichia coli K-12 (bacteria) | |||||||||
Method | single particle reconstruction / negative staining / Resolution: 28.0 Å | |||||||||
Authors | Sverzhinsky A / Chung JWC / Deme JC / Fabre L / Levey KT / Plesa M / Carter DM / Lypaczewski P / Coulton JW | |||||||||
Citation | Journal: J Bacteriol / Year: 2015 Title: Membrane Protein Complex ExbB4-ExbD1-TonB1 from Escherichia coli Demonstrates Conformational Plasticity. Authors: Aleksandr Sverzhinsky / Jacqueline W Chung / Justin C Deme / Lucien Fabre / Kristian T Levey / Maria Plesa / David M Carter / Patrick Lypaczewski / James W Coulton / Abstract: Iron acquisition at the outer membrane (OM) of Gram-negative bacteria is powered by the proton motive force (PMF) of the cytoplasmic membrane (CM), harnessed by the CM-embedded complex of ExbB, ExbD, ...Iron acquisition at the outer membrane (OM) of Gram-negative bacteria is powered by the proton motive force (PMF) of the cytoplasmic membrane (CM), harnessed by the CM-embedded complex of ExbB, ExbD, and TonB. Its stoichiometry, ensemble structural features, and mechanism of action are unknown. By panning combinatorial phage libraries, periplasmic regions of dimerization between ExbD and TonB were predicted. Using overexpression of full-length His6-tagged exbB-exbD and S-tagged tonB, we purified detergent-solubilized complexes of ExbB-ExbD-TonB from Escherichia coli. Protein-detergent complexes of ∼230 kDa with a hydrodynamic radius of ∼6.0 nm were similar to previously purified ExbB₄-ExbD₂ complexes. Significantly, they differed in electronegativity by native agarose gel electrophoresis. The stoichiometry was determined to be ExbB₄-ExbD₁-TonB₁. Single-particle electron microscopy agrees with this stoichiometry. Two-dimensional averaging supported the phage display predictions, showing two forms of ExbD-TonB periplasmic heterodimerization: extensive and distal. Three-dimensional (3D) particle classification showed three representative conformations of ExbB₄-ExbD₁-TonB₁. Based on our structural data, we propose a model in which ExbD shuttles a proton across the CM via an ExbB interprotein rearrangement. Proton translocation would be coupled to ExbD-mediated collapse of extended TonB in complex with ligand-loaded receptors in the OM, followed by repositioning of TonB through extensive dimerization with ExbD. Here we present the first report for purification of the ExbB-ExbD-TonB complex, molar ratios within the complex (4:1:1), and structural biology that provides insights into 3D organization. IMPORTANCE: Receptors in the OM of Gram-negative bacteria allow entry of iron-bound siderophores that are necessary for pathogenicity. Numerous iron-acquisition strategies rely upon a ubiquitous and ...IMPORTANCE: Receptors in the OM of Gram-negative bacteria allow entry of iron-bound siderophores that are necessary for pathogenicity. Numerous iron-acquisition strategies rely upon a ubiquitous and unique protein for energization: TonB. Complexed with ExbB and ExbD, the Ton system links the PMF to OM transport. Blocking iron uptake by targeting a vital nanomachine holds promise in therapeutics. Despite much research, the stoichiometry, structural arrangement, and molecular mechanism of the CM-embedded ExbB-ExbD-TonB complex remain unreported. Here we demonstrate in vitro evidence of ExbB₄-ExbD₁-TonB₁ complexes. Using 3D EM, we reconstructed the complex in three conformational states that show variable ExbD-TonB heterodimerization. Our structural observations form the basis of a model for TonB-mediated iron acquisition. | |||||||||
History |
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-Structure visualization
Movie |
Movie viewer |
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Structure viewer | EM map: SurfViewMolmilJmol/JSmol |
Supplemental images |
-Downloads & links
-EMDB archive
Map data | emd_2859.map.gz | 6.6 MB | EMDB map data format | |
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Header (meta data) | emd-2859-v30.xml emd-2859.xml | 12.1 KB 12.1 KB | Display Display | EMDB header |
Images | ExbBExbDTonBDDM_extensdimer_coloured_imagenew.tif | 67.5 KB | ||
Archive directory | http://ftp.pdbj.org/pub/emdb/structures/EMD-2859 ftp://ftp.pdbj.org/pub/emdb/structures/EMD-2859 | HTTPS FTP |
-Validation report
Summary document | emd_2859_validation.pdf.gz | 203.1 KB | Display | EMDB validaton report |
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Full document | emd_2859_full_validation.pdf.gz | 202.3 KB | Display | |
Data in XML | emd_2859_validation.xml.gz | 5.4 KB | Display | |
Arichive directory | https://ftp.pdbj.org/pub/emdb/validation_reports/EMD-2859 ftp://ftp.pdbj.org/pub/emdb/validation_reports/EMD-2859 | HTTPS FTP |
-Related structure data
-Links
EMDB pages | EMDB (EBI/PDBe) / EMDataResource |
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-Map
File | Download / File: emd_2859.map.gz / Format: CCP4 / Size: 7.8 MB / Type: IMAGE STORED AS FLOATING POINT NUMBER (4 BYTES) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Annotation | ExbB4-ExbD1-TonB1 complex with extensive dimerization between ExbD and TonB periplasmic domains | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Projections & slices | Image control
Images are generated by Spider. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Voxel size | X=Y=Z: 2.2 Å | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Density |
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Symmetry | Space group: 1 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Details | EMDB XML:
CCP4 map header:
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-Supplemental data
-Sample components
-Entire : Membrane protein complex ExbB4-ExbD1-TonB1 from Escherichia coli
Entire | Name: Membrane protein complex ExbB4-ExbD1-TonB1 from Escherichia coli |
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Components |
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-Supramolecule #1000: Membrane protein complex ExbB4-ExbD1-TonB1 from Escherichia coli
Supramolecule | Name: Membrane protein complex ExbB4-ExbD1-TonB1 from Escherichia coli type: sample / ID: 1000 Oligomeric state: Four ExbB in complex with one ExbD and one TonB Number unique components: 3 |
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Molecular weight | Theoretical: 150 KDa |
-Macromolecule #1: Biopolymer Transport Protein ExbB
Macromolecule | Name: Biopolymer Transport Protein ExbB / type: protein_or_peptide / ID: 1 / Name.synonym: ExbB / Number of copies: 4 / Oligomeric state: Tetramer / Recombinant expression: Yes |
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Source (natural) | Organism: Escherichia coli K-12 (bacteria) / Location in cell: Cytoplasmic Membrane |
Molecular weight | Theoretical: 26 KDa |
Recombinant expression | Organism: Escherichia coli BL21(DE3) (bacteria) / Recombinant strain: pLysS / Recombinant plasmid: pETDuet-1 |
Sequence | UniProtKB: Biopolymer transport protein ExbB / GO: membrane => GO:0016020 / InterPro: TonB-system energizer ExbB type-1 |
-Macromolecule #2: Biopolymer Transport Protein ExbD
Macromolecule | Name: Biopolymer Transport Protein ExbD / type: protein_or_peptide / ID: 2 / Name.synonym: ExbD / Number of copies: 1 / Oligomeric state: Monomer / Recombinant expression: Yes |
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Source (natural) | Organism: Escherichia coli K-12 (bacteria) / Location in cell: Cytoplasmic Membrane |
Molecular weight | Theoretical: 17 KDa |
Recombinant expression | Organism: Escherichia coli BL21(DE3) (bacteria) / Recombinant strain: pLysS / Recombinant plasmid: pETDuet-1 |
Sequence | UniProtKB: Biopolymer transport protein ExbD / GO: membrane => GO:0016020 / InterPro: TonB system transport protein ExbD type-1 |
-Macromolecule #3: Protein TonB
Macromolecule | Name: Protein TonB / type: protein_or_peptide / ID: 3 / Name.synonym: TonB / Number of copies: 1 / Oligomeric state: Monomer / Recombinant expression: Yes |
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Source (natural) | Organism: Escherichia coli K-12 (bacteria) / Location in cell: Cytoplasmic Membrane |
Molecular weight | Theoretical: 29 KDa |
Recombinant expression | Organism: Escherichia coli BL21(DE3) (bacteria) / Recombinant strain: pLysS / Recombinant plasmid: pETDuet-1 |
Sequence | UniProtKB: Protein TonB / GO: membrane => GO:0016020 / InterPro: TonB/TolA, C-terminal |
-Experimental details
-Structure determination
Method | negative staining |
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Processing | single particle reconstruction |
Aggregation state | particle |
-Sample preparation
Buffer | pH: 7.5 / Details: 25 mM Tris-HCl, 150 mM NaCl, 0.02% DDM |
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Staining | Type: NEGATIVE Details: Grids with adsorbed protein were stained with 1.5% uranyl formate for 90 seconds. |
Grid | Details: 400 mesh copper grid with thin carbon support, glow discharged |
Vitrification | Cryogen name: NONE / Instrument: OTHER |
-Electron microscopy
Microscope | FEI TECNAI F20 |
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Alignment procedure | Legacy - Astigmatism: Objective lens astigmatism was corrected at 50,000x magnification |
Date | Apr 22, 2014 |
Image recording | Category: CCD / Film or detector model: GATAN ULTRASCAN 4000 (4k x 4k) / Average electron dose: 20 e/Å2 |
Electron beam | Acceleration voltage: 200 kV / Electron source: FIELD EMISSION GUN |
Electron optics | Calibrated magnification: 67147 / Illumination mode: FLOOD BEAM / Imaging mode: BRIGHT FIELD / Cs: 2.0 mm / Nominal defocus max: 3.0 µm / Nominal defocus min: 1.0 µm / Nominal magnification: 67000 |
Sample stage | Specimen holder: Room temperature / Specimen holder model: SIDE ENTRY, EUCENTRIC |
Experimental equipment | Model: Tecnai F20 / Image courtesy: FEI Company |
-Image processing
Details | Manual particle picking from random conical tilt pairs, 3D classification, projection matching angular refinement |
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CTF correction | Details: Each Micrograph |
Final reconstruction | Applied symmetry - Point group: C1 (asymmetric) / Algorithm: OTHER / Resolution.type: BY AUTHOR / Resolution: 28.0 Å / Resolution method: FSC 0.143 CUT-OFF / Software - Name: Xmipp3.1, RELION1.3 / Number images used: 9400 |