6D42

Crystal structure of the KCa3.1 C-terminal four-helix bundle (with copper)


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.75014 Å
  • R-Value Free: 0.323 
  • R-Value Work: 0.252 

wwPDB Validation 3D Report Full Report


This is version 1.0 of the entry. See complete history

Literature

Crystal structure of the C-terminal four-helix bundle of the potassium channel KCa3.1.

Ji, T.Corbalan-Garcia, S.Hubbard, S.R.

(2018) PLoS ONE 13: e0199942-e0199942

  • DOI: 10.1371/journal.pone.0199942

  • PubMed Abstract: 
  • KCa3.1 (also known as SK4 or IK1) is a mammalian intermediate-conductance potassium channel that plays a critical role in the activation of T cells, B cells, and mast cells, effluxing potassium ions to maintain a negative membrane potential for influ ...

    KCa3.1 (also known as SK4 or IK1) is a mammalian intermediate-conductance potassium channel that plays a critical role in the activation of T cells, B cells, and mast cells, effluxing potassium ions to maintain a negative membrane potential for influxing calcium ions. KCa3.1 shares primary sequence similarity with three other (low-conductance) potassium channels: KCa2.1, KCa2.2, and KCa2.3 (also known as SK1-3). These four homotetrameric channels bind calmodulin (CaM) in the cytoplasmic region, and calcium binding to CaM triggers channel activation. Unique to KCa3.1, activation also requires phosphorylation of a single histidine residue, His358, in the cytoplasmic region, which relieves copper-mediated inhibition of the channel. Near the cytoplasmic C-terminus of KCa3.1 (and KCa2.1-2.3), secondary-structure analysis predicts the presence of a coiled-coil/heptad repeat. Here, we report the crystal structure of the C-terminal coiled-coil region of KCa3.1, which forms a parallel four-helix bundle, consistent with the tetrameric nature of the channel. Interestingly, the four copies of a histidine residue, His389, in an 'a' position within the heptad repeat, are observed to bind a copper ion along the four-fold axis of the bundle. These results suggest that His358, the inhibitory histidine in KCa3.1, might coordinate a copper ion through a similar binding mode.


    Organizational Affiliation

    Kimmel Center for Biology and Medicine of the Skirball Institute, Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, United States of America.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Intermediate conductance calcium-activated potassium channel protein 4
A, B
42Homo sapiensMutation(s): 0 
Gene Names: KCNN4 (IK1, IKCA1, KCA4, SK4)
Find proteins for O15554 (Homo sapiens)
Go to Gene View: KCNN4
Go to UniProtKB:  O15554
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
CU
Query on CU

Download SDF File 
Download CCD File 
A, B
COPPER (II) ION
Cu
JPVYNHNXODAKFH-UHFFFAOYSA-N
 Ligand Interaction
Modified Residues  1 Unique
IDChainsTypeFormula2D DiagramParent
MSE
Query on MSE
A, B
L-PEPTIDE LINKINGC5 H11 N O2 SeMET
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.75014 Å
  • R-Value Free: 0.323 
  • R-Value Work: 0.252 
  • Space Group: P 4 21 2
Unit Cell:
Length (Å)Angle (°)
a = 37.590α = 90.00
b = 37.590β = 90.00
c = 116.946γ = 90.00
Software Package:
Software NamePurpose
HKL-2000data reduction
Cootmodel building
HKL-2000data scaling
PHENIXrefinement
PHENIXphasing

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History & Funding Information

Deposition Data

  • Deposited Date: 2018-04-17 
  • Released Date: 2018-07-11 
  • Deposition Author(s): Hubbard, S.R., Ji, T.

Funding OrganizationLocationGrant Number
National Institutes of Health/National Institute Of Allergy and Infectious DiseasesUnited StatesR21AI107443

Revision History 

  • Version 1.0: 2018-07-11
    Type: Initial release