5J03

Crystal Structure of a chimeric Kv7.2 - Kv7.3 proximal C-terminal Domain in Complex with Calmodulin


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2 Å
  • R-Value Free: 0.228 
  • R-Value Work: 0.179 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

Structural Insights into the M-Channel Proximal C-Terminus/Calmodulin Complex.

Strulovich, R.Tobelaim, W.S.Attali, B.Hirsch, J.A.

(2016) Biochemistry 55: 5353-5365

  • DOI: 10.1021/acs.biochem.6b00477

  • PubMed Abstract: 
  • The Kv7 (KCNQ) channel family, comprising voltage-gated potassium channels, plays major roles in fine-tuning cellular excitability by reducing firing frequency and controlling repolarization. Kv7 channels have a unique intracellular C-terminal (CT) d ...

    The Kv7 (KCNQ) channel family, comprising voltage-gated potassium channels, plays major roles in fine-tuning cellular excitability by reducing firing frequency and controlling repolarization. Kv7 channels have a unique intracellular C-terminal (CT) domain bound constitutively by calmodulin (CaM). This domain plays key functions in channel tetramerization, trafficking, and gating. CaM binds to the proximal CT, comprising helices A and B. Kv7.2 and Kv7.3 are expressed in neural tissues. Together, they form the heterotetrameric M channel. We characterized Kv7.2, Kv7.3, and chimeric Kv7.3 helix A-Kv7.2 helix B (Q3A-Q2B) proximal CT/CaM complexes by solution methods at various Ca(2+)concentrations and determined them all to have a 1:1 stoichiometry. We then determined the crystal structure of the Q3A-Q2B/CaM complex at high Ca(2+) concentration to 2.0 Å resolution. CaM hugs the antiparallel coiled coil of helices A and B, braced together by an additional helix. The structure displays a hybrid apo-Ca(2+) CaM conformation even though four Ca(2+) ions are bound. Our results pinpoint unique interactions enabling the possible intersubunit pairing of Kv7.3 helix A and Kv7.2 helix B while underlining the potential importance of Kv7.3 helix A's role in stabilizing channel oligomerization. Also, the structure can be used to rationalize various channelopathic mutants. Functional testing of the chimeric channel found it to have a voltage-dependence similar to the M channel, thereby demonstrating helix A's importance in imparting gating properties.


    Organizational Affiliation

    Department of Biochemistry and Molecular Biology, Institute of Structural Biology, George S. Wise Faculty of Life Sciences, ‡Department of Physiology and Pharmacology, Sackler Faculty of Medicine, and §Sagol School of Neuroscience, Tel Aviv University , Ramat Aviv 69978, Israel.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Potassium voltage-gated channel subfamily KQT member 3,Potassium voltage-gated channel subfamily KQT member 2
A
110Homo sapiensMutation(s): 0 
Gene Names: KCNQ3, KCNQ2
Find proteins for O43525 (Homo sapiens)
Go to Gene View: KCNQ3
Go to UniProtKB:  O43525
Find proteins for O43526 (Homo sapiens)
Go to Gene View: KCNQ2
Go to UniProtKB:  O43526
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
Calmodulin
B
149Homo sapiensMutation(s): 0 
Gene Names: CALM2 (CAM2, CAMB)
Find proteins for P0DP24 (Homo sapiens)
Go to Gene View: CALM2
Go to UniProtKB:  P0DP24
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
ACT
Query on ACT

Download SDF File 
Download CCD File 
B
ACETATE ION
C2 H3 O2
QTBSBXVTEAMEQO-UHFFFAOYSA-M
 Ligand Interaction
CA
Query on CA

Download SDF File 
Download CCD File 
B
CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2 Å
  • R-Value Free: 0.228 
  • R-Value Work: 0.179 
  • Space Group: P 31 2 1
Unit Cell:
Length (Å)Angle (°)
a = 47.665α = 90.00
b = 47.665β = 90.00
c = 182.216γ = 120.00
Software Package:
Software NamePurpose
XDSdata reduction
MOLREPphasing
SCALAdata scaling
PHENIXrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
DFGGermany--
Israel Science FoundationIsrael1519/12

Revision History 

  • Version 1.0: 2016-09-07
    Type: Initial release
  • Version 1.1: 2016-10-05
    Type: Database references