Biological Assembly 1  

 3D View: Structure | 1D-3D View | Electron Density | Validation Report | Ligand Interaction | Predict Membrane 

Global Symmetry: Cyclic - C4  (3D View)
Global Stoichiometry: Homo 4-mer - A4 

Biological assembly 1 assigned by authors and generated by PISA (software)

Macromolecule Content

• Total Structure Weight: 34.12 kDa 
• Atom Count: 2218 
• Modelled Residue Count: 280 
• Deposited Residue Count: 301 
• Unique protein chains: 1

3ZRS

X-ray crystal structure of a KirBac potassium channel highlights a mechanism of channel opening at the bundle-crossing gate.

• PDB DOI: 10.2210/pdb3ZRS/pdb

• Classification: METAL TRANSPORT
• Organism(s): Magnetospirillum magnetotacticum
• Expression System: Escherichia coli BL21(DE3)
• Mutation(s): Yes 
• Membrane Protein: Yes  OPMPDBTMMemProtMDmpstruc


• Deposited: 2011-06-17 Released: 2012-01-11 
• Deposition Author(s): Bavro, V.N., De Zorzi, R., Schmidt, M.R., Muniz, J.R.C., Zubcevic, L., Sansom, M.S.P., Venien-Bryan, C., Tucker, S.J.

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Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 3.05 Å
• R-Value Free: 0.259 
• R-Value Work: 0.220 
• R-Value Observed: 0.222 

Literature

Structure of a Kirbac Potassium Channel with an Open Bundle Crossing Indicates a Mechanism of Channel Gating

Bavro, V.N., De Zorzi, R., Schmidt, M.R., Muniz, J.R.C., Zubcevic, L., Sansom, M.S.P., Venien-Bryan, C., Tucker, S.J.

(2012) Nat Struct Mol Biol 19: 158

• PubMed: 22231399 
• DOI: 10.1038/nsmb.2208
• Primary Citation of Related Structures:  
  3ZRS


• PubMed Abstract: 
  

KirBac channels are prokaryotic homologs of mammalian inwardly rectifying (Kir) potassium channels, and recent crystal structures of both Kir and KirBac channels have provided major insight into their unique structural architecture. However, all of the available structures are closed at the helix bundle crossing, and therefore the structural mechanisms that control opening of their primary activation gate remain unknown. In this study, we engineered the inner pore-lining helix (TM2) of KirBac3.1 to trap the bundle crossing in an apparently open conformation and determined the crystal structure of this mutant channel to 3.05 Å resolution. Contrary to previous speculation, this new structure suggests a mechanistic model in which rotational 'twist' of the cytoplasmic domain is coupled to opening of the bundle-crossing gate through a network of inter- and intrasubunit interactions that involve the TM2 C-linker, slide helix, G-loop and the CD loop.

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Organizational Affiliation: 

Clarendon Laboratory, Department of Physics, University of Oxford, Oxford, UK.

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
ATP-SENSITIVE INWARD RECTIFIER POTASSIUM CHANNEL 10	A	301	Magnetospirillum magnetotacticum	Mutation(s): 1  Membrane Entity: Yes
UniProt
Find proteins for D9N164 (Magnetospirillum magnetotacticum) Explore D9N164  Go to UniProtKB:  D9N164

Small Molecules

Ligands 2 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram
K	D [auth A], E [auth A], F [auth A], G [auth A], H [auth A]	POTASSIUM ION K NPYPAHLBTDXSSS-UHFFFAOYSA-N
CL	B [auth A], C [auth A]	CHLORIDE ION Cl VEXZGXHMUGYJMC-UHFFFAOYSA-M

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 3.05 Å
• R-Value Free: 0.259 
• R-Value Work: 0.220 
• R-Value Observed: 0.222 
• Space Group: P 4 2₁ 2

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 106.24	α = 90
b = 106.24	β = 90
c = 89.8	γ = 90

Software Package:

Software Name	Purpose
BUSTER	refinement
MOSFLM	data reduction
SCALA	data scaling
PHASER	phasing

Structure Validation

Entry History 

Deposition Data

• Deposited Date: 2011-06-17 
• Released Date: 2012-01-11 
Deposition Author(s): Bavro, V.N., De Zorzi, R., Schmidt, M.R., Muniz, J.R.C., Zubcevic, L., Sansom, M.S.P., Venien-Bryan, C., Tucker, S.J.

Revision History  

• Version 1.0: 2012-01-11
  Type: Initial release
  
• Version 1.1: 2012-02-15
  Changes: Other