1NNF

Crystal Structure Analysis of Haemophlius Influenzae Ferric-ion Binding Protein H9Q Mutant Form

Summary for 1NNF

• Entry DOI: 10.2210/pdb1nnf/pdb
• Descriptor: Iron-utilization periplasmic protein, FE (III) ION, {[-(BIS-CARBOXYMETHYL-AMINO)-ETHYL]-CARBOXYMETHYL-AMINO}-ACETIC ACID, ... (4 entities in total)
• Functional Keywords: iron-binding protein, edta-fe-protein complex, metal binding protein
• Biological source: Haemophilus influenzae
• Cellular location: Periplasm (Probable): P35755
• Total number of polymer chains: 1
• Total formula weight: 34107.32

Authors

Shouldice, S.R.,Dougan, D.R.,Skene, R.J.,Tari, L.W.,McRee, D.E.,Yu, R.-H.,Schryvers, A.B. (deposition date: 2003-01-13, release date: 2003-04-01, Last modification date: 2023-08-16)

Primary citation

Shouldice, S.R.,Dougan, D.R.,Skene, R.J.,Tari, L.W.,McRee, D.E.,Yu, R.-H.,Schryvers, A.B.
High Resolution Structure of an Alternate Form of the Ferric ion Binding Protein from Haemophilus influenzae
J.Biol.Chem., 278:11513-11519, 2003

PubMed Abstract: The periplasmic iron binding protein of pathogenic Gram-negative bacteria performs an essential role in iron acquisition from transferrin and other iron sources. Structural analysis of this protein from Haemophilus influenzae identified four amino acids that ligand the bound iron: His(9), Glu(57), Tyr(195), and Tyr(196). A phosphate provides an additional ligand, and the presence of a water molecule is required to complete the octahedral geometry for stable iron binding. We report the 1.14-A resolution crystal structure of the iron-loaded form of the H. influenzae periplasmic ferric ion binding protein (FbpA) mutant H9Q. This protein was produced in the periplasm of Escherichia coli and, after purification and conversion to the apo form, was iron-loaded. H9Q is able to bind ferric iron in an open conformation. A surprising finding in the present high resolution structure is the presence of EDTA located at the previously determined anion ternary binding site, where phosphate is located in the wild type holo and apo structures. EDTA contributes four of the six coordinating ligands for iron, with two Tyr residues, 195 and 196, completing the coordination. This is the first example of a metal binding protein with a bound metal.EDTA complex. The results suggest that FbpA may have the ability to bind and transport iron bound to biological chelators, in addition to bare ferric iron.

PubMed: 12533539
DOI: 10.1074/jbc.M211780200

Experimental method

X-RAY DIFFRACTION (1.1 Å)