Selective coordination of cobalt ions by zinc fingers in Escherichia coli

The ability of peptides to coordinate with specific metal ions is crucial for environmental protection and recycling processes, because of the toxicity and scarcity of the ions. One-third of proteins in biological systems have binding affinities to specific metal ions, and thus, can be further applied to collect precious metal ions. Zinc ion is a necessary co-factor for the regulation of physiological responses in biological systems, because of its ability to bind biomolecules. In this study, three zinc finger (ZF) domains (PARIS_ZF2-4) from Parkin-interacting substrates (PARIS) were used to harvest heterometals such as Co²⁺, Cu²⁺, and Fe³⁺ in Escherichia coli. Spectroscopic results demonstrated that PARIS_ZF2-4 can coordinate with Co²⁺ during expression. Purified PARIS_ZF2-4 generated specific d–d transition bands (570 and 644 nm), which were monitored upon the addition of Co²⁺ to apo-PARIS_ZF2-4. These results can facilitate the possible applications of the ZF domain in heterometal substitution and elimination in biological systems.