1NTF

Crystal Structure of Cimex Nitrophorin


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.8 Å
  • R-Value Free: 0.198 
  • R-Value Work: 0.151 

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.USA 102: 594-599

  • DOI: 10.1073/pnas.0406549102
  • Primary Citation of Related Structures:  1Y21
  • Also Cited By: 2IMQ

  • 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 prot ...

    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.Mol.Biol. 7: 551


    Organizational Affiliation

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




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
salivary nitrophorin
A
282Cimex lectulariusN/A
Find proteins for O76745 (Cimex lectularius)
Go to UniProtKB:  O76745
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
HEM
Query on HEM

Download SDF File 
Download CCD File 
A
PROTOPORPHYRIN IX CONTAINING FE
HEME
C34 H32 Fe N4 O4
KABFMIBPWCXCRK-RGGAHWMASA-L
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.8 Å
  • R-Value Free: 0.198 
  • R-Value Work: 0.151 
  • Space Group: P 1 21 1
Unit Cell:
Length (Å)Angle (°)
a = 49.200α = 90.00
b = 42.100β = 95.88
c = 65.850γ = 90.00
Software Package:
Software NamePurpose
REFMACrefinement
d*TREKdata scaling
CrystalCleardata reduction
MLPHAREphasing

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

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