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Publication Abstract from PubMed

The use of protein cages for the creation of novel inorganic nanomaterials has attracted considerable attention in recent years. Ferritins are among the most commonly used protein cages in nanoscience. Accordingly, the binding of various metals to ferritins has been studied extensively. Dps (DNA-binding protein from starved cells)-like proteins belong to the ferritin superfamily. In contrast to ferritins, Dps-like proteins form 12-mers instead of 24-mers, have a different ferroxidase center, and are able to store a smaller amount of iron atoms in a hollow cavity (up to approximately 500, instead of the approximately 4500 iron atoms found in ferritins). With the exception of iron, the binding of other metal cations to Dps proteins has not been studied in detail. Here, the binding of six divalent metal ions (Zn(2+), Mn(2+), Ni(2+), Co(2+), Cu(2+), and Mg(2+)) to Streptococcus suisDps-like peroxide resistance protein (SsDpr) was characterized by X-ray crystallography and isothermal titration calorimetry (ITC). All metal cations, except for Mg(2+), were found to bind similarly to the ferroxidase center, with moderate affinity (binding constants between 0.1x10(5) M(-1) and 5x10(5) M(-1)). The stoichiometry of binding, as deduced by ITC data, suggested the presence of a dication ferroxidase site. No other metal binding sites were identified in the protein. The results presented here demonstrate the ability of SsDpr to bind various metals as substitutes for iron and to help in better understanding protein-metal interactions in the Dps family of proteins as potential metal nanocontainers.

Structural and Thermodynamic Characterization of Metal Ion Binding in Streptococcus suis Dpr.,Haikarainen T, Thanassoulas A, Stavros P, Nounesis G, Haataja S, Papageorgiou AC J Mol Biol. 2010 Nov 5. PMID:21056572^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.