4JRE

Crystal structure of nitrate/nitrite exchanger NarK with nitrite bound


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.80 Å
  • R-Value Free: 0.269 
  • R-Value Work: 0.223 
  • R-Value Observed: 0.226 

wwPDB Validation   3D Report Full Report


Ligand Structure Quality Assessment 


This is version 1.3 of the entry. See complete history


Literature

Crystal structure of a nitrate/nitrite exchanger.

Zheng, H.Wisedchaisri, G.Gonen, T.

(2013) Nature 497: 647-651

  • DOI: 10.1038/nature12139
  • Primary Citation of Related Structures:  
    4JR9, 4JRE

  • PubMed Abstract: 
  • Mineral nitrogen in nature is often found in the form of nitrate (NO3(-)). Numerous microorganisms evolved to assimilate nitrate and use it as a major source of mineral nitrogen uptake. Nitrate, which is central in nitrogen metabolism, is first reduced to nitrite (NO2(-)) through a two-electron reduction reaction ...

    Mineral nitrogen in nature is often found in the form of nitrate (NO3(-)). Numerous microorganisms evolved to assimilate nitrate and use it as a major source of mineral nitrogen uptake. Nitrate, which is central in nitrogen metabolism, is first reduced to nitrite (NO2(-)) through a two-electron reduction reaction. The accumulation of cellular nitrite can be harmful because nitrite can be reduced to the cytotoxic nitric oxide. Instead, nitrite is rapidly removed from the cell by channels and transporters, or reduced to ammonium or dinitrogen through the action of assimilatory enzymes. Despite decades of effort no structure is currently available for any nitrate transport protein and the mechanism by which nitrate is transported remains largely unknown. Here we report the structure of a bacterial nitrate/nitrite transport protein, NarK, from Escherichia coli, with and without substrate. The structures reveal a positively charged substrate-translocation pathway lacking protonatable residues, suggesting that NarK functions as a nitrate/nitrite exchanger and that protons are unlikely to be co-transported. Conserved arginine residues comprise the substrate-binding pocket, which is formed by association of helices from the two halves of NarK. Key residues that are important for substrate recognition and transport are identified and related to extensive mutagenesis and functional studies. We propose that NarK exchanges nitrate for nitrite by a rocker switch mechanism facilitated by inter-domain hydrogen bond networks.


    Organizational Affiliation

    Janelia Farm Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, Virginia 20147, USA.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Nitrite extrusion protein 1A, D466Escherichia coli K-12Mutation(s): 0 
Gene Names: b1223JW1214narK
Membrane Entity: Yes 
UniProt
Find proteins for P10903 (Escherichia coli (strain K12))
Explore P10903 
Go to UniProtKB:  P10903
Protein Feature View
Expand
  • Reference Sequence
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetailsImage
Immunoglobulin Gamma-2a, Heavy chainB, E [auth H]217Mus musculusMutation(s): 0 
Protein Feature View
Expand
  • Reference Sequence
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 3
MoleculeChainsSequence LengthOrganismDetailsImage
Immunoglobulin Kappa, Light chainC, F [auth L]211Mus musculusMutation(s): 0 
Protein Feature View
Expand
  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
GYP (Subject of Investigation/LOI)
Query on GYP

Download Ideal Coordinates CCD File 
H [auth A], J [auth D]methyl alpha-D-glucopyranoside
C7 H14 O6
HOVAGTYPODGVJG-ZFYZTMLRSA-N
 Ligand Interaction
NO2
Query on NO2

Download Ideal Coordinates CCD File 
G [auth A], I [auth D]NITRITE ION
N O2
IOVCWXUNBOPUCH-UHFFFAOYSA-M
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.80 Å
  • R-Value Free: 0.269 
  • R-Value Work: 0.223 
  • R-Value Observed: 0.226 
  • Space Group: P 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 81.91α = 100.07
b = 81.407β = 96.38
c = 138.487γ = 115.92
Software Package:
Software NamePurpose
BOSdata collection
PHASERphasing
REFMACrefinement
HKL-2000data reduction
HKL-2000data scaling

Structure Validation

View Full Validation Report



Ligand Structure Quality Assessment  



Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2013-05-15
    Type: Initial release
  • Version 1.1: 2013-05-22
    Changes: Database references
  • Version 1.2: 2013-07-10
    Changes: Database references
  • Version 1.3: 2020-07-29
    Type: Remediation
    Reason: Carbohydrate remediation
    Changes: Data collection, Database references, Derived calculations, Structure summary