2cf7

From Proteopedia

Revision as of 17:10, 18 December 2007

ASP74ALA MUTANT CRYSTAL STRUCTURE FOR DPS-LIKE PEROXIDE RESISTANCE PROTEIN DPR FROM STREPTOCOCCUS SUIS.

Overview

The Dps-like peroxide resistance protein (Dpr) is a dodecameric protein, that protects the human and swine pathogen Streptococcus suis from, hydrogen peroxide by removing free Fe2+ from the cytosol. Subsequent, oxidation of iron by Dpr results in the deposition of Fe3+ inside the, protein's central cavity. Structural changes that occur in the ferroxidase, center were studied by X-ray crystallography after soaking Dpr crystals, with Fe2+ in the presence of sodium dithionite. Twelve iron-binding sites, were identified with each site formed by residues Asp74 and Glu78 from one, subunit, and Asp63, His47 and His59 from a 2-fold symmetry-related, subunit. Compared to the iron-free Dpr, Asp74 and Glu78 were found to be, the most flexible amino acid residues and able to adopt a variety of, conformations in different subunits. The crystal structure of an Asp74Ala, Dpr mutant soaked with a Fe2+ -solution revealed variations in the Asp63, position and no iron bound to the ferroxidase center. These results, indicate an intrinsic flexibility in the active site that may be important, for the catalytic reaction and subsequent nucleation events. Two iron, cores with remarkably different features were identified in Dpr using, X-ray absorption spectroscopy. Purified Dpr was found to have a small-size, iron core with only approximately 16 iron atoms/dodecamer forming a, ferritin-like ferrihydrite structure. Because of its size, this core, represents the smallest iron core identified so far in ferritins and other, Dps-like proteins. A large-size core (approximately 180 iron, atoms/dodecamer) formed after incubating the protein with a ferrous, solution shows differences in iron coordination compared to the small size, core. Characterization of the two iron cores in Dpr could provide insights, into nucleation events and the mechanism of iron core growth in the Dps, family of proteins.

About this Structure

2CF7 is a Single protein structure of sequence from Streptococcus suis with CA, CL and EPE as ligands. Known structural/functional Site: . Full crystallographic information is available from OCA.

Reference

Iron incorporation in Streptococcus suis Dps-like peroxide resistance protein Dpr requires mobility in the ferroxidase center and leads to the formation of a ferrihydrite-like core., Kauko A, Pulliainen AT, Haataja S, Meyer-Klaucke W, Finne J, Papageorgiou AC, J Mol Biol. 2006 Nov 17;364(1):97-109. Epub 2006 Aug 26. PMID:16997323

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