1J9S

Crystal structure of nitrite soaked oxidized H255N AFNIR


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.9 Å
  • R-Value Free: 0.204 
  • R-Value Work: 0.164 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Alternate substrate binding modes to two mutant (D98N and H255N) forms of nitrite reductase from Alcaligenes faecalis S-6: structural model of a transient catalytic intermediate

Boulanger, M.J.Murphy, M.E.

(2001) Biochemistry 40: 9132-9141

  • Primary Citation of Related Structures:  1J9Q, 1J9R, 1J9T

  • PubMed Abstract: 
  • High-resolution nitrite soaked oxidized and reduced crystal structures of two active site mutants, D98N and H255N, of nitrite reductase (NIR) from Alcaligenes faecalis S-6 were determined to better than 2.0 A resolution. In the oxidized D98N nitrite- ...

    High-resolution nitrite soaked oxidized and reduced crystal structures of two active site mutants, D98N and H255N, of nitrite reductase (NIR) from Alcaligenes faecalis S-6 were determined to better than 2.0 A resolution. In the oxidized D98N nitrite-soaked structures, nitrite is coordinated to the type II copper via its oxygen atoms in an asymmetric bidentate manner; however, elevated B-factors and weak electron density indicate that both nitrite and Asn98 are less ordered than in the native enzyme. This disorder likely results from the inability of the N delta 2 atom of Asn98 to form a hydrogen bond with the bound protonated nitrite, indicating that the hydrogen bond between Asp98 and nitrite in the native NIR structure is essential in anchoring nitrite in the active site for catalysis. In the oxidized nitrite soaked H255N crystal structure, nitrite does not displace the ligand water and is instead coordinated in an alternative mode via a single oxygen to the type II copper. His255 is clearly essential in defining the nitrite binding site despite the lack of direct interaction with the substrate in the native enzyme. The resulting pentacoordinate copper site in the H255N structure also serves as a model for a proposed transient intermediate in the catalytic mechanism consisting of a hydroxyl and nitric oxide molecule coordinated to the copper. The formation of an unusual dinuclear type I copper site in the reduced nitrite soaked D98N and H255N crystal structures may represent an evolutionary link between the mononuclear type I copper centers and dinuclear Cu(A) sites.


    Organizational Affiliation

    Department of Biochemistry & Molecular Biology, The University of British Columbia, Vancouver, BC V6T 1Z3, Canada.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
COPPER-CONTAINING NITRITE REDUCTASE
A, B, C
341Alcaligenes faecalisGene Names: nirK (nir)
EC: 1.7.2.1
Find proteins for P38501 (Alcaligenes faecalis)
Go to UniProtKB:  P38501
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
NO2
Query on NO2

Download SDF File 
Download CCD File 
A, B
NITRITE ION
N O2
IOVCWXUNBOPUCH-UHFFFAOYSA-M
 Ligand Interaction
CU
Query on CU

Download SDF File 
Download CCD File 
A, B, C
COPPER (II) ION
Cu
JPVYNHNXODAKFH-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.9 Å
  • R-Value Free: 0.204 
  • R-Value Work: 0.164 
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 62.001α = 90.00
b = 102.416β = 90.00
c = 146.305γ = 90.00
Software Package:
Software NamePurpose
CNSrefinement
DENZOdata reduction
SCALEPACKdata scaling
CNSphasing

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2001-06-06
    Type: Initial release
  • Version 1.1: 2008-04-27
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance