The zinc repository of Cupriavidus metallidurans

Zinc is a central player in the metalloproteomes of prokaryotes and eukaryotes. We used a top-down quantitative proteomic approach to reveal the repository of the zinc pools in the proteobacterium Cupriavidus metallidurans. About 60% of the theoretical proteome of C. metallidurans were identified, quantified, and compared between a ΔzupT mutant defect in zinc allocation and its parent strain. In both strains, the number of zinc-binding proteins and their binding sites exceeded that of the zinc ions per cell, indicating that the totality of the zinc proteome provides empty binding sites for incoming zinc ions. This zinc repository plays a central role in zinc homeostasis in C. metallidurans and probably also in other organisms.