2ZDO

Crystal structure of IsdG-N7A in complex with hemin


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.80 Å
  • R-Value Free: 0.234 
  • R-Value Work: 0.198 
  • R-Value Observed: 0.200 

Starting Model: experimental
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This is version 1.3 of the entry. See complete history


Literature

Ruffling of Metalloporphyrins Bound to IsdG and IsdI, Two Heme-degrading Enzymes in Staphylococcus aureus

Lee, W.C.Reniere, M.L.Skaar, E.P.Murphy, M.E.P.

(2008) J Biol Chem 283: 30957-30963

  • DOI: https://doi.org/10.1074/jbc.M709486200
  • Primary Citation of Related Structures:  
    2ZDO, 2ZDP

  • PubMed Abstract: 

    IsdG and IsdI are paralogous proteins that are intracellular components of a complex heme uptake system in Staphylococcus aureus. IsdG and IsdI were shown previously to reductively degrade hemin. Crystal structures of the apoproteins show that these proteins belong to a newly identified heme degradation family distinct from canonical eukaryotic and prokaryotic heme oxygenases. Here we report the crystal structures of an inactive N7A variant of IsdG in complex with Fe(3+)-protoporphyrin IX (IsdG-hemin) and of IsdI in complex with cobalt protoporphyrin IX (IsdI-CoPPIX) to 1.8 A or better resolution. These structures show that the metalloporphyrins are buried into similar deep clefts such that the propionic acids form salt bridges to two Arg residues. His(77) (IsdG) or His(76) (IsdI), a critical residue required for activity, is coordinated to the Fe(3+) or Co(3+) atoms, respectively. The bound porphyrin rings form extensive steric interactions in the binding cleft such that the rings are highly distorted from the plane. This distortion is best described as ruffled and places the beta- and delta-meso carbons proximal to the distal oxygen-binding site. In the IsdG-hemin structure, Fe(3+) is pentacoordinate, and the distal side is occluded by the side chain of Ile(55). However, in the structure of IsdI-CoPPIX, the distal side of the CoPPIX accommodates a chloride ion in a cavity formed through a conformational change in Ile(55). The chloride ion participates in a hydrogen bond to the side chain amide of Asn(6). Together the structures suggest a reaction mechanism in which a reactive peroxide intermediate proceeds with nucleophilic oxidation at the beta- or delta-meso carbon of the hemin.


  • Organizational Affiliation

    Department of Microbiology and Immunology, Life Sciences Institute, the University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada.


Macromolecules
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Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Heme-degrading monooxygenase isdG
A, B, C, D
109Staphylococcus aureusMutation(s): 1 
Gene Names: isdG
EC: 1.14.99.3
UniProt
Find proteins for Q7A649 (Staphylococcus aureus (strain N315))
Explore Q7A649 
Go to UniProtKB:  Q7A649
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ7A649
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.80 Å
  • R-Value Free: 0.234 
  • R-Value Work: 0.198 
  • R-Value Observed: 0.200 
  • Space Group: P 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 46.585α = 77.57
b = 58.631β = 74.39
c = 59.692γ = 75.15
Software Package:
Software NamePurpose
REFMACrefinement
Blu-Icedata collection
MOSFLMdata reduction
SCALAdata scaling
MOLREPphasing

Structure Validation

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Ligand Structure Quality Assessment 


Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2008-08-19
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance
  • Version 1.2: 2021-11-10
    Changes: Database references, Derived calculations
  • Version 1.3: 2023-11-01
    Changes: Data collection, Refinement description