The electron crystallography structure of the cAMP-bound potassium channel MloK1

Experimental Data Snapshot

  • Resolution: 7.00 Å

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Ligand-Induced Structural Changes in the Cyclic Nucleotide-Modulated Potassium Channel Mlok1

Kowal, J.Chami, M.Baumgartner, P.Arheit, M.Chiu, P.L.Rangl, M.Scheuring, S.Schroeder, G.F.Nimigean, C.M.Stahlberg, H.

(2014) Nat Commun 5: 3106

  • DOI: https://doi.org/10.1038/ncomms4106
  • Primary Citation of Related Structures:  
    4CHV, 4CHW

  • PubMed Abstract: 

    Cyclic nucleotide-modulated ion channels are important for signal transduction and pacemaking in eukaryotes. The molecular determinants of ligand gating in these channels are still unknown, mainly because of a lack of direct structural information. Here we report ligand-induced conformational changes in full-length MloK1, a cyclic nucleotide-modulated potassium channel from the bacterium Mesorhizobium loti, analysed by electron crystallography and atomic force microscopy. Upon cAMP binding, the cyclic nucleotide-binding domains move vertically towards the membrane, and directly contact the S1-S4 voltage sensor domains. This is accompanied by a significant shift and tilt of the voltage sensor domain helices. In both states, the inner pore-lining helices are in an 'open' conformation. We propose a mechanism in which ligand binding can favour pore opening via a direct interaction between the cyclic nucleotide-binding domains and voltage sensors. This offers a simple mechanistic hypothesis for the coupling between ligand gating and voltage sensing in eukaryotic HCN channels.

  • Organizational Affiliation

    Center for Cellular Imaging and NanoAnalytics, Biozentrum, University of Basel, Mattenstrasse 26, CH-4058 Basel, Switzerland.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
A, B, C, D
361Mesorhizobium lotiMutation(s): 0 
Membrane Entity: Yes 
Find proteins for Q98GN8 (Mesorhizobium japonicum (strain LMG 29417 / CECT 9101 / MAFF 303099))
Explore Q98GN8 
Go to UniProtKB:  Q98GN8
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ98GN8
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 7.00 Å
  • Space Group: P 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 104.325α = 90
b = 104.325β = 90
c = 104.325γ = 90

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2014-01-15
    Type: Initial release
  • Version 1.1: 2014-02-12
    Changes: Database references
  • Version 1.2: 2019-04-24
    Changes: Data collection, Other