6UXB

MthK N-terminal truncation state 3 bound with calcium


Experimental Data Snapshot

  • Method: ELECTRON MICROSCOPY
  • Resolution: 4.90 Å
  • Aggregation State: PARTICLE 
  • Reconstruction Method: SINGLE PARTICLE 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history


Literature

Ball-and-chain inactivation in a calcium-gated potassium channel.

Fan, C.Sukomon, N.Flood, E.Rheinberger, J.Allen, T.W.Nimigean, C.M.

(2020) Nature 580: 288-293

  • DOI: 10.1038/s41586-020-2116-0
  • Structures With Same Primary Citation

  • PubMed Abstract: 
  • Inactivation is the process by which ion channels terminate ion flux through their pores while the opening stimulus is still present 1 . In neurons, inactivation of both sodium and potassium channels is crucial for the generation of action ...

    Inactivation is the process by which ion channels terminate ion flux through their pores while the opening stimulus is still present 1 . In neurons, inactivation of both sodium and potassium channels is crucial for the generation of action potentials and regulation of firing frequency 1,2 . 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 3-7 . 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 2+ , 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 2+ -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.


    Organizational Affiliation

    Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY, USA. crn2002@med.cornell.edu.



Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Calcium-gated potassium channel MthK
A, B, C, D, E, F, G, H
336Methanothermobacter thermautotrophicusMutation(s): 0 
Gene Names: mthKMTH_1520
Find proteins for O27564 (Methanothermobacter thermautotrophicus (strain ATCC 29096 / DSM 1053 / JCM 10044 / NBRC 100330 / Delta H))
Go to UniProtKB:  O27564
Experimental Data & Validation

Experimental Data

  • Method: ELECTRON MICROSCOPY
  • Resolution: 4.90 Å
  • Aggregation State: PARTICLE 
  • Reconstruction Method: SINGLE PARTICLE 

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

  • Deposited Date: 2019-11-07 
  • Released Date: 2020-03-18 
  • Deposition Author(s): Chen, F., Crina, N.

Revision History 

  • Version 1.0: 2020-03-18
    Type: Initial release
  • Version 1.1: 2020-04-22
    Changes: Database references