Biological Assembly 1  

 3D View: Structure | 1D-3D View | Electron Density | Validation Report | Predict Membrane 

Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Monomer - A1 

Biological assembly 1 assigned by authors and generated by PISA (software)

Macromolecule Content

• Total Structure Weight: 82.71 kDa 
• Atom Count: 5182 
• Modelled Residue Count: 649 
• Deposited Residue Count: 745 
• Unique protein chains: 1

4B7O

THE FrpB IRON TRANSPORTER FROM NEISSERIA MENINGITIDIS (F5-1 VARIANT) APOPROTEIN FORM

• PDB DOI: 10.2210/pdb4B7O/pdb

• Classification: TRANSPORT PROTEIN
• Organism(s): Neisseria meningitidis
• Expression System: Escherichia coli B
• Mutation(s): No 
• Membrane Protein: Yes  OPMPDBTMMemProtMDmpstruc


• Deposited: 2012-08-21 Released: 2013-01-23 
• Deposition Author(s): Saleem, M., Prince, S.M., Derrick, J.P.

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Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 2.32 Å
• R-Value Free: 0.281 
• R-Value Work: 0.233 
• R-Value Observed: 0.236 

Literature

Use of a Molecular Decoy to Segregate Transport from Antigenicity in the Frpb Iron Transporter from Neisseria Meningitidis.

Saleem, M., Prince, S.M., Rigby, S.E.J., Imran, M., Patel, H., Chan, H., Sanders, H., Maiden, M.C.J., Feavers, I.M., Derrick, J.P.

(2013) PLoS One 8: 56746

• PubMed: 23457610 
• DOI: 10.1371/journal.pone.0056746
• Primary Citation of Related Structures:  
  4AIP, 4AIQ, 4B7O


• PubMed Abstract: 
  

FrpB is an outer membrane transporter from Neisseria meningitidis, the causative agent of meningococcal meningitis. It is a member of the TonB-dependent transporter (TBDT) family and is responsible for iron uptake into the periplasm. FrpB is subject to a high degree of antigenic variation, principally through a region of hypervariable sequence exposed at the cell surface. From the crystal structures of two FrpB antigenic variants, we identify a bound ferric ion within the structure which induces structural changes on binding which are consistent with it being the transported substrate. Binding experiments, followed by elemental analysis, verified that FrpB binds Fe(3+) with high affinity. EPR spectra of the bound Fe(3+) ion confirmed that its chemical environment was consistent with that observed in the crystal structure. Fe(3+) binding was reduced or abolished on mutation of the Fe(3+)-chelating residues. FrpB orthologs were identified in other Gram-negative bacteria which showed absolute conservation of the coordinating residues, suggesting the existence of a specific TBDT sub-family dedicated to the transport of Fe(3+). The region of antigenic hypervariability lies in a separate, external sub-domain, whose structure is conserved in both the F3-3 and F5-1 variants, despite their sequence divergence. We conclude that the antigenic sub-domain has arisen separately as a result of immune selection pressure to distract the immune response from the primary transport function. This would enable FrpB to function as a transporter independently of antibody binding, by using the antigenic sub-domain as a 'molecular decoy' to distract immune surveillance.

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Organizational Affiliation: 

Michael Smith Building, Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester, United Kingdom.

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
IRON-REGULATED OUTER MEMBRANE PROTEIN	A	745	Neisseria meningitidis	Mutation(s): 0  Gene Names: fetA Membrane Entity: Yes
UniProt
Find proteins for Q841A2 (Neisseria meningitidis) Explore Q841A2  Go to UniProtKB:  Q841A2

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 2.32 Å
• R-Value Free: 0.281 
• R-Value Work: 0.233 
• R-Value Observed: 0.236 
• Space Group: C 1 2 1

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 175.21	α = 90
b = 79.1	β = 97.58
c = 74.75	γ = 90

Software Package:

Software Name	Purpose
REFMAC	refinement
XDS	data reduction
MOLREP	phasing

Structure Validation

Entry History 

Deposition Data

• Deposited Date: 2012-08-21 
• Released Date: 2013-01-23 
Deposition Author(s): Saleem, M., Prince, S.M., Derrick, J.P.

Revision History  

• Version 1.0: 2013-01-23
  Type: Initial release
  
• Version 1.1: 2013-03-06
  Changes: Database references, Structure summary
• Version 1.2: 2013-03-20
  Changes: Database references