2O68

Crystal Structure of Haemophilus influenzae Q58L mutant FbpA

Summary for 2O68

• Entry DOI: 10.2210/pdb2o68/pdb
• Related: 1NNF 1QVS 1QW0 2O69 2O6A
• Descriptor: Iron-utilization periplasmic protein, FE (III) ION, PHOSPHATE ION, ... (4 entities in total)
• Functional Keywords: mixed beta sheet, iron binding, metal binding protein
• Biological source: Haemophilus influenzae
• Cellular location: Periplasm (Probable): P35755
• Total number of polymer chains: 1
• Total formula weight: 33905.09

Authors

Shouldice, S.R.,Tari, L.W. (deposition date: 2006-12-07, release date: 2007-04-03, Last modification date: 2023-08-30)

Primary citation

Khan, A.G.,Shouldice, S.R.,Tari, L.W.,Schryvers, A.B.
The role of the synergistic phosphate anion in iron transport by the periplasmic iron-binding protein from Haemophilus influenzae.
Biochem.J., 403:43-48, 2007

PubMed Abstract: The acquisition of iron from transferrin by Gram-negative bacterial pathogens is dependent on a periplasmic ferric-ion-binding protein, FbpA. FbpA shuttles iron from the outer membrane to an inner membrane transport complex. A bound phosphate anion completes the iron co-ordination shell of FbpA and kinetic studies demonstrate that the anion plays a critical role in iron binding and release in vitro. The present study was initiated to directly address the hypothesis that the synergistic anion is required for transport of iron in intact cells. A series of site-directed mutants in the anion-binding amino acids of the Haemophilus influenzae FbpA (Gln-58, Asn-175 and Asn-193) were prepared to provide proteins defective in binding of the phosphate anion. Crystal structures of various mutants have revealed that alteration of the C-terminal domain ligands (Asn-175 or Asn-193) but not the N-terminal domain ligand (Gln-58) abrogated binding of the phosphate anion. The mutant proteins were introduced into H. influenzae to evaluate their ability to mediate iron transport. All of the single site-directed mutants (Q58L, N175L and N193L) were capable of mediating iron acquisition from transferrin and from limiting concentrations of ferric citrate. The results suggest that the transport of iron by FbpA is not dependent on binding of phosphate in the synergistic anion-binding site.

PubMed: 17147516
DOI: 10.1042/BJ20061589

Experimental method

X-RAY DIFFRACTION (1.7 Å)