1nnf
|
Crystal Structure Analysis of Haemophlius Influenzae Ferric-ion Binding Protein H9Q Mutant Form
OverviewOverview
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.
About this StructureAbout this Structure
1NNF is a Single protein structure of sequence from Haemophilus influenzae with FE and EDT as ligands. Full crystallographic information is available from OCA.
ReferenceReference
High resolution structure of an alternate form of the ferric ion binding protein from Haemophilus influenzae., Shouldice SR, Dougan DR, Skene RJ, Tari LW, McRee DE, Yu RH, Schryvers AB, J Biol Chem. 2003 Mar 28;278(13):11513-9. Epub 2003 Jan 17. PMID:12533539
Page seeded by OCA on Tue Nov 20 22:24:37 2007