Crystal structure of holo Moraxella catarrhalis ferric binding protein A in an open conformation

Experimental Data Snapshot

  • Resolution: 1.75 Å
  • R-Value Free: 0.265 
  • R-Value Work: 0.231 

wwPDB Validation   3D Report Full Report

This is version 1.2 of the entry. See complete history


Structural and functional insights into iron acquisition from lactoferrin and transferrin in Gram-negative bacterial pathogens.

Chan, C.Ng, D.Fraser, M.E.Schryvers, A.B.

(2022) Biometals 

  • DOI: https://doi.org/10.1007/s10534-022-00466-6
  • Primary Citation of Related Structures:  
    7LI0, 7LI1

  • PubMed Abstract: 

    Iron is an essential element for various lifeforms but is largely insoluble due to the oxygenation of Earth's atmosphere and oceans during the Proterozoic era. Metazoans evolved iron transport glycoproteins, like transferrin (Tf) and lactoferrin (Lf), to keep iron in a non-toxic, usable form, while maintaining a low free iron concentration in the body that is unable to sustain bacterial growth. To survive on the mucosal surfaces of the human respiratory tract where it exclusively resides, the Gram-negative bacterial pathogen Moraxella catarrhalis utilizes surface receptors for acquiring iron directly from human Tf and Lf. The receptors are comprised of a surface lipoprotein to capture iron-loaded Tf or Lf and deliver it to a TonB-dependent transporter (TBDT) for removal of iron and transport across the outer membrane. The subsequent transport of iron into the cell is normally mediated by a periplasmic iron-binding protein and inner membrane transport complex, which has yet to be determined for Moraxella catarrhalis. We identified two potential periplasm to cytoplasm transport systems and performed structural and functional studies with the periplasmic binding proteins (FbpA and AfeA) to evaluate their role. Growth studies with strains deleted in the fbpA or afeA gene demonstrated that FbpA, but not AfeA, was required for growth on human Tf or Lf. The crystal structure of FbpA with bound iron in the open conformation was obtained, identifying three tyrosine ligands that were required for growth on Tf or Lf. Computational modeling of the YfeA homologue, AfeA, revealed conserved residues involved in metal binding.

  • Organizational Affiliation

    Department of Microbiology, Immunology and Infectious Diseases, Cumming School of Medicine, University of Calgary, Calgary, Canada.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Fe(3+) ABC transporter substrate-binding protein
A, B, C, D
312Moraxella catarrhalisMutation(s): 0 
Gene Names: fbpA
Find proteins for A0A1E9VR34 (Moraxella sp. HMSC061H09)
Explore A0A1E9VR34 
Go to UniProtKB:  A0A1E9VR34
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupA0A1E9VR34
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on CO3

Download Ideal Coordinates CCD File 
E [auth A]
F [auth A]
H [auth B]
I [auth B]
K [auth C]
E [auth A],
F [auth A],
H [auth B],
I [auth B],
K [auth C],
L [auth C],
N [auth D],
O [auth D]
C O3
FE (Subject of Investigation/LOI)
Query on FE

Download Ideal Coordinates CCD File 
G [auth A]
J [auth B]
M [auth C]
P [auth D]
Q [auth D]
G [auth A],
J [auth B],
M [auth C],
P [auth D],
Q [auth D],
R [auth D]
Experimental Data & Validation

Experimental Data

  • Resolution: 1.75 Å
  • R-Value Free: 0.265 
  • R-Value Work: 0.231 
  • Space Group: P 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 62.13α = 91.02
b = 67.56β = 92.26
c = 73.77γ = 105.02
Software Package:
Software NamePurpose
XDSdata reduction
XSCALEdata scaling

Structure Validation

View Full Validation Report

Entry History & Funding Information

Deposition Data

Funding OrganizationLocationGrant Number
Canadian Institutes of Health Research (CIHR)Canada--

Revision History  (Full details and data files)

  • Version 1.0: 2022-02-23
    Type: Initial release
  • Version 1.1: 2022-12-07
    Changes: Database references
  • Version 1.2: 2023-10-25
    Changes: Data collection, Refinement description