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- PDB-3jch: Cryo-EM structure of the magnesium channel CorA in the magnesium-... -
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Basic information
Entry | Database: PDB / ID: 3jch | ||||||
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Title | Cryo-EM structure of the magnesium channel CorA in the magnesium-free, asymmetric open state II | ||||||
![]() | Magnesium transport protein CorA | ||||||
![]() | TRANSPORT PROTEIN / membrane protein / ion channel / magnesium channel / pentameric complex / symmetry vs. asymmetry / conformational change / gating mechanism / direct electron detector / K2 | ||||||
Function / homology | ![]() cobalt ion transport / magnesium ion transmembrane transport / cobalt ion transmembrane transporter activity / magnesium ion transmembrane transporter activity / cobalt ion binding / protein homooligomerization / magnesium ion binding / identical protein binding / plasma membrane Similarity search - Function | ||||||
Biological species | ![]() ![]() | ||||||
Method | ELECTRON MICROSCOPY / single particle reconstruction / cryo EM / Resolution: 7.06 Å | ||||||
![]() | Matthies, D. / Perozo, E. / Subramaniam, S. | ||||||
![]() | ![]() Title: Cryo-EM Structures of the Magnesium Channel CorA Reveal Symmetry Break upon Gating. Authors: Doreen Matthies / Olivier Dalmas / Mario J Borgnia / Pawel K Dominik / Alan Merk / Prashant Rao / Bharat G Reddy / Shahidul Islam / Alberto Bartesaghi / Eduardo Perozo / Sriram Subramaniam / ![]() Abstract: CorA, the major Mg(2+) uptake system in prokaryotes, is gated by intracellular Mg(2+) (KD ∼ 1-2 mM). X-ray crystallographic studies of CorA show similar conformations under Mg(2+)-bound and Mg(2+)- ...CorA, the major Mg(2+) uptake system in prokaryotes, is gated by intracellular Mg(2+) (KD ∼ 1-2 mM). X-ray crystallographic studies of CorA show similar conformations under Mg(2+)-bound and Mg(2+)-free conditions, but EPR spectroscopic studies reveal large Mg(2+)-driven quaternary conformational changes. Here, we determined cryo-EM structures of CorA in the Mg(2+)-bound closed conformation and in two open Mg(2+)-free states at resolutions of 3.8, 7.1, and 7.1 Å, respectively. In the absence of bound Mg(2+), four of the five subunits are displaced to variable extents (∼ 10-25 Å) by hinge-like motions as large as ∼ 35° at the stalk helix. The transition between a single 5-fold symmetric closed state and an ensemble of low Mg(2+), open, asymmetric conformational states is, thus, the key structural signature of CorA gating. This mechanism is likely to apply to other structurally similar divalent ion channels. | ||||||
History |
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Structure visualization
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Structure viewer | Molecule: ![]() ![]() |
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PDBx/mmCIF format | ![]() | 231.1 KB | Display | ![]() |
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PDB format | ![]() | 139.4 KB | Display | ![]() |
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-Validation report
Summary document | ![]() | 763.1 KB | Display | ![]() |
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Full document | ![]() | 763.7 KB | Display | |
Data in XML | ![]() | 40.7 KB | Display | |
Data in CIF | ![]() | 66.7 KB | Display | |
Arichive directory | ![]() ![]() | HTTPS FTP |
-Related structure data
Related structure data | ![]() 6553MC ![]() 6551C ![]() 6552C ![]() 3jcfC ![]() 3jcgC M: map data used to model this data C: citing same article ( |
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Similar structure data |
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Assembly
Deposited unit | ![]()
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Components
#1: Protein | Mass: 41498.082 Da / Num. of mol.: 5 Source method: isolated from a genetically manipulated source Source: (gene. exp.) ![]() ![]() ![]() ![]() |
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-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: CorA from Thermotoga maritima in the absence of magnesium, state II Type: COMPLEX / Details: One homopentamer of CorA / Synonym: CorA |
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Molecular weight | Value: 0.2 MDa / Experimental value: NO |
Buffer solution | Name: 50 mM HEPES, pH 7.3, 150 mM NaCl, 1 mM EDTA, 0.5 mM DDM pH: 7.3 Details: 50 mM HEPES, pH 7.3, 150 mM NaCl, 1 mM EDTA, 0.5 mM DDM |
Specimen | Conc.: 3.7 mg/ml / Embedding applied: NO / Shadowing applied: NO / Staining applied: NO / Vitrification applied: YES |
Specimen support | Details: 300 mesh Cu R1.2/1.3 holey carbon grids from Quantifoil, plasma-cleaned |
Vitrification | Instrument: LEICA EM GP / Cryogen name: ETHANE / Temp: 90 K / Humidity: 86 % Details: Grids were blotted at 4 degrees Celsius for 7 seconds after a 10-second pre-blotting period, then plunge-frozen in liquid ethane. Method: Grids were blotted at 4 degrees Celsius for 7 seconds after a 10-second pre-blotting period, then plunge-frozen in liquid ethane. |
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Electron microscopy imaging
Experimental equipment | ![]() Model: Titan Krios / Image courtesy: FEI Company |
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Microscopy | Model: FEI TITAN KRIOS / Date: Oct 15, 2014 / Details: Parallel beam illumination |
Electron gun | Electron source: ![]() |
Electron lens | Mode: BRIGHT FIELD / Nominal magnification: 105000 X / Calibrated magnification: 105000 X / Nominal defocus max: 2700 nm / Nominal defocus min: 890 nm / Cs: 2.7 mm Astigmatism: Objective lens astigmatism was corrected at 105,000 times magnification. |
Specimen holder | Specimen holder model: FEI TITAN KRIOS AUTOGRID HOLDER / Specimen holder type: Liquid nitrogen-cooled / Temperature: 79.7 K / Temperature (max): 79.8 K / Temperature (min): 79.6 K |
Image recording | Electron dose: 40 e/Å2 / Film or detector model: GATAN K2 QUANTUM (4k x 4k) / Details: post-column Quantum GIF |
EM imaging optics | Energyfilter name: GIF / Energyfilter upper: 20 eV / Energyfilter lower: 0 eV |
Image scans | Num. digital images: 2498 |
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Processing
EM software |
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CTF correction | Details: CTF parameters obtained from whole micrograph | |||||||||||||||
Symmetry | Point symmetry: C1 (asymmetric) | |||||||||||||||
3D reconstruction | Method: RELION / Resolution: 7.06 Å / Resolution method: FSC 0.143 CUT-OFF / Num. of particles: 27416 / Nominal pixel size: 1.352 Å / Actual pixel size: 1.352 Å Details: Final maps were calculated from two merged datasets. (Single particle details: The particles were selected using an automatic selection program. 3D classification, 3D refinement, and ...Details: Final maps were calculated from two merged datasets. (Single particle details: The particles were selected using an automatic selection program. 3D classification, 3D refinement, and postprocessing were done using RELION 1.3.) (Single particle--Applied symmetry: C1) Symmetry type: POINT | |||||||||||||||
Atomic model building | Space: REAL | |||||||||||||||
Refinement step | Cycle: LAST
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