3DWJ

Heme-proximal W188H mutant of inducible nitric oxide synthase


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.75 Å
  • R-Value Free: 0.294 
  • R-Value Work: 0.226 
  • R-Value Observed: 0.229 

Starting Model: experimental
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Ligand Structure Quality Assessment 


This is version 1.3 of the entry. See complete history


Literature

Stabilization and Characterization of a Heme-Oxy Reaction Intermediate in Inducible Nitric-oxide Synthase

Tejero, J.Biswas, A.Wang, Z.Q.Page, R.C.Haque, M.M.Hemann, C.Zweier, J.L.Misra, S.Stuehr, D.J.

(2008) J Biol Chem 283: 33498-33507

  • DOI: https://doi.org/10.1074/jbc.M806122200
  • Primary Citation of Related Structures:  
    3DWJ

  • PubMed Abstract: 

    Nitric-oxide synthases (NOS) are heme-thiolate enzymes that N-hydroxylate L-arginine (L-Arg) to make NO. NOS contain a unique Trp residue whose side chain stacks with the heme and hydrogen bonds with the heme thiolate. To understand its importance we substituted His for Trp188 in the inducible NOS oxygenase domain (iNOSoxy) and characterized enzyme spectral, thermodynamic, structural, kinetic, and catalytic properties. The W188H mutation had relatively small effects on l-Arg binding and on enzyme heme-CO and heme-NO absorbance spectra, but increased the heme midpoint potential by 88 mV relative to wild-type iNOSoxy, indicating it decreased heme-thiolate electronegativity. The protein crystal structure showed that the His188 imidazole still stacked with the heme and was positioned to hydrogen bond with the heme thiolate. Analysis of a single turnover L-Arg hydroxylation reaction revealed that a new heme species formed during the reaction. Its build up coincided kinetically with the disappearance of the enzyme heme-dioxy species and with the formation of a tetrahydrobiopterin (H4B) radical in the enzyme, whereas its subsequent disappearance coincided with the rate of l-Arg hydroxylation and formation of ferric enzyme. We conclude: (i) W188H iNOSoxy stabilizes a heme-oxy species that forms upon reduction of the heme-dioxy species by H4B. (ii) The W188H mutation hinders either the processing or reactivity of the heme-oxy species and makes these steps become rate-limiting for l-Arg hydroxylation. Thus, the conserved Trp residue in NOS may facilitate formation and/or reactivity of the ultimate hydroxylating species by tuning heme-thiolate electronegativity.


  • Organizational Affiliation

    Department of Pathobiology, The Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Nitric oxide synthase, inducible
A, B
431Mus musculusMutation(s): 1 
Gene Names: Nos2Inosl
EC: 1.14.13.39
UniProt & NIH Common Fund Data Resources
Find proteins for P29477 (Mus musculus)
Explore P29477 
Go to UniProtKB:  P29477
IMPC:  MGI:97361
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP29477
Sequence Annotations
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  • Reference Sequence
Small Molecules
Ligands 4 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
HEM
Query on HEM

Download Ideal Coordinates CCD File 
E [auth A],
H [auth B]
PROTOPORPHYRIN IX CONTAINING FE
C34 H32 Fe N4 O4
KABFMIBPWCXCRK-RGGAHWMASA-L
H4B
Query on H4B

Download Ideal Coordinates CCD File 
F [auth A],
I [auth B]
5,6,7,8-TETRAHYDROBIOPTERIN
C9 H15 N5 O3
FNKQXYHWGSIFBK-RPDRRWSUSA-N
SO4
Query on SO4

Download Ideal Coordinates CCD File 
C [auth A]SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L
NH4
Query on NH4

Download Ideal Coordinates CCD File 
D [auth A],
G [auth B]
AMMONIUM ION
H4 N
QGZKDVFQNNGYKY-UHFFFAOYSA-O
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.75 Å
  • R-Value Free: 0.294 
  • R-Value Work: 0.226 
  • R-Value Observed: 0.229 
  • Space Group: P 61 2 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 214.597α = 90
b = 214.597β = 90
c = 111.933γ = 120
Software Package:
Software NamePurpose
PHENIXrefinement
d*TREKdata reduction
d*TREKdata scaling
PHENIXphasing

Structure Validation

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Ligand Structure Quality Assessment 


Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2008-09-30
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance
  • Version 1.2: 2021-10-20
    Changes: Database references, Derived calculations
  • Version 1.3: 2023-08-30
    Changes: Data collection, Refinement description