Crystal Structure of the Potassium Transporter TrkH from Vibrio parahaemolyticus

Experimental Data Snapshot

  • Resolution: 3.51 Å
  • R-Value Free: 0.299 
  • R-Value Work: 0.249 
  • R-Value Observed: 0.252 

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Crystal structure of a potassium ion transporter, TrkH.

Cao, Y.Jin, X.Huang, H.Derebe, M.G.Levin, E.J.Kabaleeswaran, V.Pan, Y.Punta, M.Love, J.Weng, J.Quick, M.Ye, S.Kloss, B.Bruni, R.Martinez-Hackert, E.Hendrickson, W.A.Rost, B.Javitch, J.A.Rajashankar, K.R.Jiang, Y.Zhou, M.

(2011) Nature 471: 336-340

  • DOI: https://doi.org/10.1038/nature09731
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    The TrkH/TrkG/KtrB proteins mediate K(+) uptake in bacteria and probably evolved from simple K(+) channels by multiple gene duplications or fusions. Here we present the crystal structure of a TrkH from Vibrio parahaemolyticus. TrkH is a homodimer, and each protomer contains an ion permeation pathway. A selectivity filter, similar in architecture to those of K(+) channels but significantly shorter, is lined by backbone and side-chain oxygen atoms. Functional studies showed that TrkH is selective for permeation of K(+) and Rb(+) over smaller ions such as Na(+) or Li(+). Immediately intracellular to the selectivity filter are an intramembrane loop and an arginine residue, both highly conserved, which constrict the permeation pathway. Substituting the arginine with an alanine significantly increases the rate of K(+) flux. These results reveal the molecular basis of K(+) selectivity and suggest a novel gating mechanism for this large and important family of membrane transport proteins.

  • Organizational Affiliation

    Department of Physiology & Cellular Biophysics, College of Physicians and Surgeons, Columbia University, 630 West 168th Street, New York, New York 10032, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Potassium uptake protein TrkH
A, B
494Vibrio parahaemolyticusMutation(s): 0 
Gene Names: VP0032
Membrane Entity: Yes 
Find proteins for Q87TN7 (Vibrio parahaemolyticus serotype O3:K6 (strain RIMD 2210633))
Explore Q87TN7 
Go to UniProtKB:  Q87TN7
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ87TN7
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 3.51 Å
  • R-Value Free: 0.299 
  • R-Value Work: 0.249 
  • R-Value Observed: 0.252 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 91.489α = 90
b = 97.406β = 90
c = 195.653γ = 90
Software Package:
Software NamePurpose
SCALEPACKdata scaling
PDB_EXTRACTdata extraction
ADSCdata collection
DENZOdata reduction

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2011-01-19
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance
  • Version 1.2: 2017-11-08
    Changes: Refinement description