3SZ6

IsdX1, an anthrax hemophore


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.8 Å
  • R-Value Free: 0.234 
  • R-Value Work: 0.209 

wwPDB Validation 3D Report Full Report


This is version 1.0 of the entry. See complete history

Literature

Differential function of lip residues in the mechanism and biology of an anthrax hemophore.

Ekworomadu, M.T.Poor, C.B.Owens, C.P.Balderas, M.A.Fabian, M.Olson, J.S.Murphy, F.Balkabasi, E.Honsa, E.S.He, C.Goulding, C.W.Maresso, A.W.

(2012) Plos Pathog. 8: e1002559-e1002559

  • DOI: 10.1371/journal.ppat.1002559
  • Primary Citation of Related Structures:  3SIK

  • PubMed Abstract: 
  • To replicate in mammalian hosts, bacterial pathogens must acquire iron. The majority of iron is coordinated to the protoporphyrin ring of heme, which is further bound to hemoglobin. Pathogenic bacteria utilize secreted hemophores to acquire heme from ...

    To replicate in mammalian hosts, bacterial pathogens must acquire iron. The majority of iron is coordinated to the protoporphyrin ring of heme, which is further bound to hemoglobin. Pathogenic bacteria utilize secreted hemophores to acquire heme from heme sources such as hemoglobin. Bacillus anthracis, the causative agent of anthrax disease, secretes two hemophores, IsdX1 and IsdX2, to acquire heme from host hemoglobin and enhance bacterial replication in iron-starved environments. Both proteins contain NEAr-iron Transporter (NEAT) domains, a conserved protein module that functions in heme acquisition in Gram-positive pathogens. Here, we report the structure of IsdX1, the first of a Gram-positive hemophore, with and without bound heme. Overall, IsdX1 forms an immunoglobin-like fold that contains, similar to other NEAT proteins, a 3(10)-helix near the heme-binding site. Because the mechanistic function of this helix in NEAT proteins is not yet defined, we focused on the contribution of this region to hemophore and NEAT protein activity, both biochemically and biologically in cultured cells. Site-directed mutagenesis of amino acids in and adjacent to the helix identified residues important for heme and hemoglobin association, with some mutations affecting both properties and other mutations affecting only heme stabilization. IsdX1 with mutations that reduced the ability to associate with hemoglobin and bind heme failed to restore the growth of a hemophore-deficient strain of B. anthracis on hemoglobin as the sole iron source. These data indicate that not only is the 3(10)-helix important for NEAT protein biology, but also that the processes of hemoglobin and heme binding can be both separate as well as coupled, the latter function being necessary for maximal heme-scavenging activity. These studies enhance our understanding of NEAT domain and hemophore function and set the stage for structure-based inhibitor design to block NEAT domain interaction with upstream ligands.


    Organizational Affiliation

    Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Conserved domain protein
A, B
121Bacillus anthracisN/A
Find proteins for Q81L44 (Bacillus anthracis)
Go to UniProtKB:  Q81L44
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
CL
Query on CL

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Download CCD File 
A, B
CHLORIDE ION
Cl
VEXZGXHMUGYJMC-UHFFFAOYSA-M
 Ligand Interaction
GOL
Query on GOL

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Download CCD File 
B
GLYCEROL
GLYCERIN; PROPANE-1,2,3-TRIOL
C3 H8 O3
PEDCQBHIVMGVHV-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.8 Å
  • R-Value Free: 0.234 
  • R-Value Work: 0.209 
  • Space Group: P 1
Unit Cell:
Length (Å)Angle (°)
a = 36.637α = 99.24
b = 43.659β = 96.53
c = 47.408γ = 107.35
Software Package:
Software NamePurpose
ADSCdata collection
PHASERphasing
SCALEPACKdata scaling
HKL-2000data reduction
PHENIXrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2012-03-28
    Type: Initial release