2Q9U

Crystal structure of the flavodiiron protein from Giardia intestinalis


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.90 Å
  • R-Value Free: 0.204 
  • R-Value Work: 0.165 
  • R-Value Observed: 0.167 

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This is version 1.1 of the entry. See complete history


Literature

The O2-scavenging flavodiiron protein in the human parasite Giardia intestinalis

Di Matteo, A.Scandurra, F.M.Testa, F.Forte, E.Sarti, P.Brunori, M.Giuffre, A.

(2008) J Biol Chem 283: 4061-4068

  • DOI: 10.1074/jbc.M705605200
  • Primary Citation of Related Structures:  
    2Q9U

  • PubMed Abstract: 
  • The flavodiiron proteins (FDP) are widespread among strict or facultative anaerobic prokaryotes, where they are involved in the response to nitrosative and/or oxidative stress. Unexpectedly, FDPs were fairly recently identified in a restricted group of microaerobic protozoa, including Giardia intestinalis, the causative agent of the human infectious disease giardiasis ...

    The flavodiiron proteins (FDP) are widespread among strict or facultative anaerobic prokaryotes, where they are involved in the response to nitrosative and/or oxidative stress. Unexpectedly, FDPs were fairly recently identified in a restricted group of microaerobic protozoa, including Giardia intestinalis, the causative agent of the human infectious disease giardiasis. The FDP from Giardia was expressed, purified, and extensively characterized by x-ray crystallography, stopped-flow spectroscopy, respirometry, and NO amperometry. Contrary to flavorubredoxin, the FDP from Escherichia coli, the enzyme from Giardia has high O(2)-reductase activity (>40 s(-1)), but very low NO-reductase activity (approximately 0.2 s(-1)); O(2) reacts with the reduced protein quite rapidly (milliseconds) and with high affinity (K(m) < or = 2 microM), producing H(2)O. The three-dimensional structure of the oxidized protein determined at 1.9A resolution shows remarkable similarities with prokaryotic FDPs. Consistent with HPLC analysis, the enzyme is a dimer of dimers with FMN and the non-heme di-iron site topologically close at the monomer-monomer interface. Unlike the FDP from Desulfovibrio gigas, the residue His-90 is a ligand of the di-iron site, in contrast with the proposal that ligation of this histidine is crucial for a preferential specificity for NO. We propose that in G. intestinalis the primary function of FDP is to efficiently scavenge O(2), allowing this microaerobic parasite to survive in the human small intestine, thus promoting its pathogenicity.


    Organizational Affiliation

    Department of Biochemical Sciences, CNR Institute of Molecular Biology and Pathology and Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza, University of Rome, Rome I-00185, Italy.



Macromolecules
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Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
A-type flavoproteinA, B414Giardia intestinalisMutation(s): 0 
Gene Names: fprA
UniProt
Find proteins for Q86QZ1 (Giardia intestinalis)
Explore Q86QZ1 
Go to UniProtKB:  Q86QZ1
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ86QZ1
Protein Feature View
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.90 Å
  • R-Value Free: 0.204 
  • R-Value Work: 0.165 
  • R-Value Observed: 0.167 
  • Space Group: P 21 21 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 111.967α = 90
b = 115.059β = 90
c = 67.732γ = 90
Software Package:
Software NamePurpose
ADSCdata collection
MOLREPphasing
REFMACrefinement
DENZOdata reduction
SCALEPACKdata scaling

Structure Validation

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Ligand Structure Quality Assessment 



Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2007-12-11
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance