1NTF

Crystal Structure of Cimex Nitrophorin


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.80 Å
  • R-Value Free: 0.198 
  • R-Value Work: 0.151 
  • R-Value Observed: 0.153 

wwPDB Validation   3D Report Full Report


This is version 1.2 of the entry. See complete history


Literature

Heme-assisted S-nitrosation of a proximal thiolate in a nitric oxide transport protein.

Weichsel, A.Maes, E.M.Andersen, J.F.Valenzuela, J.G.Shokhireva, T.K.Walker, F.A.Montfort, W.R.

(2005) Proc Natl Acad Sci U S A 102: 594-599

  • DOI: 10.1073/pnas.0406549102
  • Primary Citation of Related Structures:  
    1NTF, 1Y21

  • PubMed Abstract: 
  • Certain bloodsucking insects deliver nitric oxide (NO) while feeding, to induce vasodilation and inhibit blood coagulation. We have expressed, characterized, and determined the crystal structure of the Cimex lectularius (bedbug) nitrophorin, the protein responsible for NO storage and delivery, to understand how the insect successfully handles this reactive molecule ...

    Certain bloodsucking insects deliver nitric oxide (NO) while feeding, to induce vasodilation and inhibit blood coagulation. We have expressed, characterized, and determined the crystal structure of the Cimex lectularius (bedbug) nitrophorin, the protein responsible for NO storage and delivery, to understand how the insect successfully handles this reactive molecule. Surprisingly, NO binds not only to the ferric nitrophorin heme, but it can also be stored as an S-nitroso (SNO) conjugate of the proximal heme cysteine (Cys-60) when present at higher concentrations. EPR- and UV-visible spectroscopies, and a crystallographic structure determination to 1.75-A resolution, reveal SNO formation to proceed with reduction of the heme iron, yielding an Fe-NO complex. Stopped-flow kinetic measurements indicate that an ordered reaction mechanism takes place: initial NO binding occurs at the ferric heme and is followed by heme reduction, Cys-60 release from the heme iron, and SNO formation. Release of NO occurs through a reversal of these steps. These data provide, to our knowledge, the first view of reversible metal-assisted SNO formation in a protein and suggest a mechanism for its role in NO release from ferrous heme. This mechanism and Cimex nitrophorin structure are completely unlike those of the nitrophorins from Rhodnius prolixus, where NO protection is provided by a large conformational change that buries the heme nitrosyl complex, highlighting the remarkable evolution of proteins that assist insects in bloodfeeding.


    Related Citations: 
    • Nitric Oxide Binding to Nitrophorin 4 Induces Complete Distal Pocket Burial
      Weichsel, A., Andersen, J.F., Roberts, S.A., Montfort, W.R.
      (2000) Nat Struct Biol 7: 551

    Organizational Affiliation

    Department of Biochemistry and Molecular Biophysics, University of Arizona, Tucson, AZ 85721, USA.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
salivary nitrophorinA282Cimex lectulariusMutation(s): 0 
UniProt
Find proteins for O76745 (Cimex lectularius)
Explore O76745 
Go to UniProtKB:  O76745
Protein Feature View
Expand
  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
HEM (Subject of Investigation/LOI)
Query on HEM

Download Ideal Coordinates CCD File 
B [auth A]PROTOPORPHYRIN IX CONTAINING FE
C34 H32 Fe N4 O4
KABFMIBPWCXCRK-RGGAHWMASA-L
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.80 Å
  • R-Value Free: 0.198 
  • R-Value Work: 0.151 
  • R-Value Observed: 0.153 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 49.2α = 90
b = 42.1β = 95.88
c = 65.85γ = 90
Software Package:
Software NamePurpose
REFMACrefinement
CrystalCleardata reduction
d*TREKdata scaling
MLPHAREphasing

Structure Validation

View Full Validation Report




Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2004-03-16
    Type: Initial release
  • Version 1.1: 2008-04-29
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance