4LCU

Structure of KcsA with E118A mutation


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.75 Å
  • R-Value Free: 0.216 
  • R-Value Work: 0.183 
  • R-Value Observed: 0.185 

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This is version 1.2 of the entry. See complete history


Literature

Molecular interactions involved in proton-dependent gating in KcsA potassium channels.

Posson, D.J.Thompson, A.N.McCoy, J.G.Nimigean, C.M.

(2013) J Gen Physiol 142: 613-624

  • DOI: https://doi.org/10.1085/jgp.201311057
  • Primary Citation of Related Structures:  
    4LBE, 4LCU

  • PubMed Abstract: 

    The bacterial potassium channel KcsA is gated open by the binding of protons to amino acids on the intracellular side of the channel. We have identified, via channel mutagenesis and x-ray crystallography, two pH-sensing amino acids and a set of nearby residues involved in molecular interactions that influence gating. We found that the minimal mutation of one histidine (H25) and one glutamate (E118) near the cytoplasmic gate completely abolished pH-dependent gating. Mutation of nearby residues either alone or in pairs altered the channel's response to pH. In addition, mutations of certain pairs of residues dramatically increased the energy barriers between the closed and open states. We proposed a Monod-Wyman-Changeux model for proton binding and pH-dependent gating in KcsA, where H25 is a "strong" sensor displaying a large shift in pKa between closed and open states, and E118 is a "weak" pH sensor. Modifying model parameters that are involved in either the intrinsic gating equilibrium or the pKa values of the pH-sensing residues was sufficient to capture the effects of all mutations.


  • Organizational Affiliation

    Department of Anesthesiology, 2 Department of Physiology and Biophysics, and 3 Department of Biochemistry, Weill Cornell Medical College, New York, NY 10065.


Macromolecules
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Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Fab light chain219Mus musculusMutation(s): 0 
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Entity ID: 2
MoleculeChains Sequence LengthOrganismDetailsImage
Fab heavy chain212Mus musculusMutation(s): 0 
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Entity ID: 3
MoleculeChains Sequence LengthOrganismDetailsImage
pH-gated potassium channel KcsA131Streptomyces lividansMutation(s): 1 
Gene Names: kcsAskc1
Membrane Entity: Yes 
UniProt
Find proteins for P0A334 (Streptomyces lividans)
Explore P0A334 
Go to UniProtKB:  P0A334
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP0A334
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.75 Å
  • R-Value Free: 0.216 
  • R-Value Work: 0.183 
  • R-Value Observed: 0.185 
  • Space Group: I 4
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 155.952α = 90
b = 155.952β = 90
c = 75.952γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling
PHASERphasing
PHENIXrefinement
PDB_EXTRACTdata extraction
HKL-2000data collection

Structure Validation

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Ligand Structure Quality Assessment 


Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2013-10-30
    Type: Initial release
  • Version 1.1: 2014-02-05
    Changes: Database references
  • Version 1.2: 2017-11-15
    Changes: Refinement description