+Open data
-Basic information
Entry | Database: EMDB / ID: EMD-20930 | |||||||||
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Title | MthK N-terminal truncation state 1 bound with calcium | |||||||||
Map data | MthK N-terminal truncation state 1 bound with calcium | |||||||||
Sample |
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Keywords | MthK / TRANSPORT PROTEIN | |||||||||
Function / homology | Function and homology information monoatomic cation transmembrane transporter activity / potassium ion transport / identical protein binding / metal ion binding / plasma membrane Similarity search - Function | |||||||||
Biological species | Methanothermobacter thermautotrophicus (archaea) | |||||||||
Method | single particle reconstruction / cryo EM / Resolution: 6.7 Å | |||||||||
Authors | Chen F / Crina N | |||||||||
Citation | Journal: Nature / Year: 2020 Title: Ball-and-chain inactivation in a calcium-gated potassium channel. Authors: Chen Fan / Nattakan Sukomon / Emelie Flood / Jan Rheinberger / Toby W Allen / Crina M Nimigean / Abstract: Inactivation is the process by which ion channels terminate ion flux through their pores while the opening stimulus is still present. In neurons, inactivation of both sodium and potassium channels is ...Inactivation is the process by which ion channels terminate ion flux through their pores while the opening stimulus is still present. In neurons, inactivation of both sodium and potassium channels is crucial for the generation of action potentials and regulation of firing frequency. A cytoplasmic domain of either the channel or an accessory subunit is thought to plug the open pore to inactivate the channel via a 'ball-and-chain' mechanism. Here we use cryo-electron microscopy to identify the molecular gating mechanism in calcium-activated potassium channels by obtaining structures of the MthK channel from Methanobacterium thermoautotrophicum-a purely calcium-gated and inactivating channel-in a lipid environment. In the absence of Ca, we obtained a single structure in a closed state, which was shown by atomistic simulations to be highly flexible in lipid bilayers at ambient temperature, with large rocking motions of the gating ring and bending of pore-lining helices. In Ca-bound conditions, we obtained several structures, including multiple open-inactivated conformations, further indication of a highly dynamic protein. These different channel conformations are distinguished by rocking of the gating rings with respect to the transmembrane region, indicating symmetry breakage across the channel. Furthermore, in all conformations displaying open channel pores, the N terminus of one subunit of the channel tetramer sticks into the pore and plugs it, with free energy simulations showing that this is a strong interaction. Deletion of this N terminus leads to functionally non-inactivating channels and structures of open states without a pore plug, indicating that this previously unresolved N-terminal peptide is responsible for a ball-and-chain inactivation mechanism. | |||||||||
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_20930.map.gz | 3.9 MB | EMDB map data format | |
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Header (meta data) | emd-20930-v30.xml emd-20930.xml | 9.5 KB 9.5 KB | Display Display | EMDB header |
Images | emd_20930.png | 119.3 KB | ||
Filedesc metadata | emd-20930.cif.gz | 5 KB | ||
Archive directory | http://ftp.pdbj.org/pub/emdb/structures/EMD-20930 ftp://ftp.pdbj.org/pub/emdb/structures/EMD-20930 | HTTPS FTP |
-Validation report
Summary document | emd_20930_validation.pdf.gz | 356.2 KB | Display | EMDB validaton report |
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Full document | emd_20930_full_validation.pdf.gz | 355.8 KB | Display | |
Data in XML | emd_20930_validation.xml.gz | 5.9 KB | Display | |
Data in CIF | emd_20930_validation.cif.gz | 6.7 KB | Display | |
Arichive directory | https://ftp.pdbj.org/pub/emdb/validation_reports/EMD-20930 ftp://ftp.pdbj.org/pub/emdb/validation_reports/EMD-20930 | HTTPS FTP |
-Related structure data
Related structure data | 6ux7MC 6u5nC 6u5pC 6u5rC 6u68C 6u6dC 6u6eC 6u6hC 6uwnC 6ux4C 6uxaC 6uxbC M: atomic model generated by this map C: citing same article (ref.) |
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Similar structure data |
-Links
EMDB pages | EMDB (EBI/PDBe) / EMDataResource |
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Related items in Molecule of the Month |
-Map
File | Download / File: emd_20930.map.gz / Format: CCP4 / Size: 52.7 MB / Type: IMAGE STORED AS FLOATING POINT NUMBER (4 BYTES) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Annotation | MthK N-terminal truncation state 1 bound with calcium | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Projections & slices | Image control
Images are generated by Spider. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Voxel size | X=Y=Z: 1.07 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 : MthK N-terminal truncation bound with calcium
Entire | Name: MthK N-terminal truncation bound with calcium |
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Components |
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-Supramolecule #1: MthK N-terminal truncation bound with calcium
Supramolecule | Name: MthK N-terminal truncation bound with calcium / type: complex / ID: 1 / Parent: 0 / Macromolecule list: all |
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Source (natural) | Organism: Methanothermobacter thermautotrophicus (archaea) |
-Macromolecule #1: Calcium-gated potassium channel MthK
Macromolecule | Name: Calcium-gated potassium channel MthK / type: protein_or_peptide / ID: 1 / Number of copies: 8 / Enantiomer: LEVO |
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Source (natural) | Organism: Methanothermobacter thermautotrophicus (archaea) |
Molecular weight | Theoretical: 37.35616 KDa |
Recombinant expression | Organism: Escherichia coli (E. coli) |
Sequence | String: MVLVIEIIRK HLPRVLKVPA TRILLLVLAV IIYGTAGFHF IEGESWTVSL YWTFVTIATV GYGDYSPSTP LGMYFTVTLI VLGIGTFAV AVERLLEFLI NREQMKLMGL IDVAKSRHVV ICGWSESTLE CLRELRGSEV FVLAEDENVR KKVLRSGANF V HGDPTRVS ...String: MVLVIEIIRK HLPRVLKVPA TRILLLVLAV IIYGTAGFHF IEGESWTVSL YWTFVTIATV GYGDYSPSTP LGMYFTVTLI VLGIGTFAV AVERLLEFLI NREQMKLMGL IDVAKSRHVV ICGWSESTLE CLRELRGSEV FVLAEDENVR KKVLRSGANF V HGDPTRVS DLEKANVRGA RAVIVDLESD SETIHCILGI RKIDESVRII AEAERYENIE QLRMAGADQV ISPFVISGRL MS RSIDDGY EAMFVQDVLA EESTRRMVEV PIPEGSKLEG VSVLDADIHD VTGVIIIGVG RGDELIIDPP RDYSFRAGDI ILG IGKPEE IERLKNYISA UniProtKB: Calcium-gated potassium channel MthK |
-Experimental details
-Structure determination
Method | cryo EM |
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Processing | single particle reconstruction |
Aggregation state | particle |
-Sample preparation
Buffer | pH: 8.5 |
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Grid | Details: unspecified |
Vitrification | Cryogen name: ETHANE |
-Electron microscopy
Microscope | FEI TITAN KRIOS |
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Image recording | Film or detector model: GATAN K2 SUMMIT (4k x 4k) / Detector mode: COUNTING / Average electron dose: 1.425 e/Å2 |
Electron beam | Acceleration voltage: 300 kV / Electron source: FIELD EMISSION GUN |
Electron optics | Illumination mode: FLOOD BEAM / Imaging mode: BRIGHT FIELD |
Experimental equipment | Model: Titan Krios / Image courtesy: FEI Company |
-Image processing
Startup model | Type of model: INSILICO MODEL |
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Final reconstruction | Applied symmetry - Point group: C1 (asymmetric) / Resolution.type: BY AUTHOR / Resolution: 6.7 Å / Resolution method: FSC 0.143 CUT-OFF / Software - Name: RELION (ver. 3) / Number images used: 40536 |
Initial angle assignment | Type: PROJECTION MATCHING |
Final angle assignment | Type: PROJECTION MATCHING |