Diamond-shaped octameric structure of KtrA with ADP bound

Experimental Data Snapshot

  • Resolution: 2.93 Å
  • R-Value Free: 0.278 
  • R-Value Work: 0.252 
  • R-Value Observed: 0.253 

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This is version 1.2 of the entry. See complete history


The structure of the KtrAB potassium transporter

Vieira-Pires, R.S.Szollosi, A.Morais-Cabral, J.H.

(2013) Nature 496: 323-328

  • DOI: https://doi.org/10.1038/nature12055
  • Primary Citation of Related Structures:  
    4J7C, 4J90, 4J91

  • PubMed Abstract: 

    In bacteria, archaea, fungi and plants the Trk, Ktr and HKT ion transporters are key components of osmotic regulation, pH homeostasis and resistance to drought and high salinity. These ion transporters are functionally diverse: they can function as Na(+) or K(+) channels and possibly as cation/K(+) symporters. They are closely related to potassium channels both at the level of the membrane protein and at the level of the cytosolic regulatory domains. Here we describe the crystal structure of a Ktr K(+) transporter, the KtrAB complex from Bacillus subtilis. The structure shows the dimeric membrane protein KtrB assembled with a cytosolic octameric KtrA ring bound to ATP, an activating ligand. A comparison between the structure of KtrAB-ATP and the structures of the isolated full-length KtrA protein with ATP or ADP reveals a ligand-dependent conformational change in the octameric ring, raising new ideas about the mechanism of activation in these transporters.

  • Organizational Affiliation

    Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, Porto 4150-180, Portugal.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Ktr system potassium uptake protein A
A, B, C, D
222Bacillus subtilis subsp. subtilis str. 168Mutation(s): 0 
Gene Names: ktrAyuaABSU31090
Membrane Entity: Yes 
Find proteins for O32080 (Bacillus subtilis (strain 168))
Explore O32080 
Go to UniProtKB:  O32080
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupO32080
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.93 Å
  • R-Value Free: 0.278 
  • R-Value Work: 0.252 
  • R-Value Observed: 0.253 
  • Space Group: C 1 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 147.932α = 90
b = 84.63β = 128.37
c = 113.675γ = 90
Software Package:
Software NamePurpose
SCALAdata scaling
PDB_EXTRACTdata extraction
DNAdata collection
XSCALEdata scaling

Structure Validation

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Ligand Structure Quality Assessment 

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2013-04-17
    Type: Initial release
  • Version 1.1: 2013-08-07
    Changes: Database references
  • Version 1.2: 2023-11-08
    Changes: Data collection, Database references, Derived calculations, Refinement description