Metalloproteomics for identification of metallodrug binding proteins

Abstract

Metallomics and metalloproteomics are emerging fields addressing the molecular mechanism of metal- related life processes and the entirety of metal/metalloid species within a cell or tissue type (1,2). By comparative proteomic analysis of H. pylori cells before and after treatment with colloidal bismuth subcitrate (CBS), we found that eight proteins are significantly up- or down-regulated. Using immobilized-metal affinity chromatography (Bi- and Ni-IMAC), we isolated and subsequently identified seven bismuth-binding proteins from H. pylori extracts (3). One of the binding proteins, HspA(or GroES), was then overexpressed to validate the methodology. Recombinant H. pylori HspA was found to bind both Ni2+ and Bi3+ at its C-terminal histidine- and cysteine-rich domain of the proteins (4). Moreover, we also found that a novel zinc-binding site by negative selection induces the metallodrug susceptibility of the protein (5). Binding of the metallodrug to other histidine-rich and related proteins will also be discussed (6). This work was supported by RGC of Hong Kong (HKU7043/06P, HKU2/06C, HKU1/07C, HKU7042/07P, HKU7038/08P, HKU7049/09P, and N_HKU752/09), Croucher Foundation and the University of Hong Kong.