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- EMDB-3864: Negative stain electron microscopy reconstruction of a cellulose ... -
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Open data
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Basic information
Entry | Database: EMDB / ID: EMD-3864 | |||||||||||||||
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Title | Negative stain electron microscopy reconstruction of a cellulose secretion (Bcs) macrocomplex from E. coli | |||||||||||||||
![]() | Bcs macrocomplex encompassing most inner-membrane and cytosolic components of the E. coli cellulose secretion system. Negative-stain EM | |||||||||||||||
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Biological species | ![]() ![]() | |||||||||||||||
Method | single particle reconstruction / negative staining / Resolution: 16.7 Å | |||||||||||||||
![]() | Krasteva PV / Fronzes R | |||||||||||||||
Funding support | ![]()
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![]() | ![]() Title: Insights into the structure and assembly of a bacterial cellulose secretion system. Authors: Petya Violinova Krasteva / Joaquin Bernal-Bayard / Laetitia Travier / Fernando Ariel Martin / Pierre-Alexandre Kaminski / Gouzel Karimova / Rémi Fronzes / Jean-Marc Ghigo / ![]() ![]() Abstract: Secreted exopolysaccharides present important determinants for bacterial biofilm formation, survival, and virulence. Cellulose secretion typically requires the concerted action of a c-di-GMP- ...Secreted exopolysaccharides present important determinants for bacterial biofilm formation, survival, and virulence. Cellulose secretion typically requires the concerted action of a c-di-GMP-responsive inner membrane synthase (BcsA), an accessory membrane-anchored protein (BcsB), and several additional Bcs components. Although the BcsAB catalytic duo has been studied in great detail, its interplay with co-expressed subunits remains enigmatic. Here we show that E. coli Bcs proteins partake in a complex protein interaction network. Electron microscopy reveals a stable, megadalton-sized macromolecular assembly, which encompasses most of the inner membrane and cytosolic Bcs components and features a previously unobserved asymmetric architecture. Heterologous reconstitution and mutational analyses point toward a structure-function model, where accessory proteins regulate secretion by affecting both the assembly and stability of the system. Altogether, these results lay the foundation for more comprehensive models of synthase-dependent exopolysaccharide secretion in biofilms and add a sophisticated secretory nanomachine to the diverse bacterial arsenal for virulence and adaptation. | |||||||||||||||
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 | ![]() | 5 MB | ![]() | |
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Header (meta data) | ![]() ![]() | 13.6 KB 13.6 KB | Display Display | ![]() |
FSC (resolution estimation) | ![]() | 7.3 KB | Display | ![]() |
Images | ![]() | 48.8 KB | ||
Archive directory | ![]() ![]() | HTTPS FTP |
-Validation report
Summary document | ![]() | 222.8 KB | Display | ![]() |
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Full document | ![]() | 221.9 KB | Display | |
Data in XML | ![]() | 9.7 KB | Display | |
Arichive directory | ![]() ![]() | HTTPS FTP |
-Related structure data
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Links
EMDB pages | ![]() ![]() |
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Map
File | ![]() | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Annotation | Bcs macrocomplex encompassing most inner-membrane and cytosolic components of the E. coli cellulose secretion system. Negative-stain EM | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Projections & slices | Image control
Images are generated by Spider. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Voxel size | X=Y=Z: 1.9 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 : Protein macrocomplex encompassing most cytosolic and inner-membra...
Entire | Name: Protein macrocomplex encompassing most cytosolic and inner-membrane components of the E. coli system for cellulose secretion |
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Components |
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-Supramolecule #1: Protein macrocomplex encompassing most cytosolic and inner-membra...
Supramolecule | Name: Protein macrocomplex encompassing most cytosolic and inner-membrane components of the E. coli system for cellulose secretion type: complex / ID: 1 / Parent: 0 Details: Protein macrocomplex encompassing cytosolic (BcsRQEF) and inner-membrane (BcsAB) components. Isolated from purified and detergent-solubilised E. coli 1094 membranes using FLAG-tagged BcsA as ...Details: Protein macrocomplex encompassing cytosolic (BcsRQEF) and inner-membrane (BcsAB) components. Isolated from purified and detergent-solubilised E. coli 1094 membranes using FLAG-tagged BcsA as bait. Stabilised by gentle glutaraldehyde cross-linking over a density gradient (GraFix). |
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Source (natural) | Organism: ![]() ![]() |
Recombinant expression | Organism: ![]() ![]() |
Molecular weight | Theoretical: 1.4 MDa |
-Experimental details
-Structure determination
Method | negative staining |
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![]() | single particle reconstruction |
Aggregation state | particle |
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Sample preparation
Concentration | 0.1 mg/mL |
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Buffer | pH: 8 Details: 20 mM HEPES pH 8.0 120 mM NaCl, 10%-40% glycerol, 5 mM MgCl2 10 uM AppCp 2 uM cyclic c-di-GMP cOmplete protease inhibitors |
Staining | Type: NEGATIVE / Material: Uranyl Acetate Details: 5 micrometers of sample were spotted on glow-discharged carbon-coated copper grids. After 1 minutes the liquid was blotted off and the sample was stained by quick passage through 3 drops of ...Details: 5 micrometers of sample were spotted on glow-discharged carbon-coated copper grids. After 1 minutes the liquid was blotted off and the sample was stained by quick passage through 3 drops of 2% uranyl acetate. The sample was left for 20-30 seconds on the last drop of stain, after which the liquid was blotted off and the sample was allowed to air-dry |
Grid | Material: COPPER / Mesh: 400 / Support film - Material: CARBON / Support film - topology: CONTINUOUS / Pretreatment - Type: GLOW DISCHARGE / Pretreatment - Atmosphere: AIR / Details: 7mA, 10 microns |
Details | Sample was purified from pelleted and solubilised membrane fractions of the E. coli 1094 2K7 BcsA-HA-FLAG strain using anti-FLAG affinity gel, 3xFLAG peptide elution and glycerol gradient purification coupled with gentle glutaraldehyde cross-linking (GraFix). Sample was monodisperse and subjected to thin-layer uranyl acetate staining. |
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Electron microscopy
Microscope | FEI TECNAI F20 |
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Image recording | Film or detector model: FEI FALCON II (4k x 4k) / Number grids imaged: 2 / Average electron dose: 12.0 e/Å2 |
Electron beam | Acceleration voltage: 200 kV / Electron source: ![]() |
Electron optics | Calibrated defocus min: 0.5 µm / Illumination mode: FLOOD BEAM / Imaging mode: BRIGHT FIELD / Nominal defocus max: 4.0 µm / Nominal magnification: 50000 |
Sample stage | Specimen holder model: OTHER / Cooling holder cryogen: NITROGEN |
Experimental equipment | ![]() Model: Tecnai F20 / Image courtesy: FEI Company |