By incorporating synthetic molecules into a protein scaffold, the resulting designer enzymes have successfully demonstrated abiological catalysis with high selectivity. In this presentation, however, we will show how to leverage proteins as sophisticated molecular ligands to construct entirely abiological metal architectures, rather than merely using them as reaction compartments.
Using human macrophage migration inhibitory factor (MIF) as our scaffold, we employed systematic computational geometrical screening and quantum-chemical calculations to identify optimal positions for histidine substitutions that would coordinate zinc ions in a geometry inspired by synthetic trinuclear zinc complexes - a structural motif absent in natural metalloenzymes.
X-ray crystallography confirmed the successful formation of the designed metal center, displaying remarkable geometric similarity to our computational model with an RMSD of 0.900 Å.
Importantly, the obtained designer tri-zinc enzyme exhibits hydrolytic activity as a non-native function while maintaining the native function. Since conventional strategies often focus on optimizing newly installed catalytic functions, the intrinsic function of the natural protein has often been sacrificed for a new function.
This work illustrates a design strategy where proteins can be exploited not just as reaction compartments but as sophisticated three-dimensional ligands capable of organizing metal ions into precise geometries. Additionally, given that proteins like MIF play important roles in biological systems, our dual-functional designer enzyme paves the way for the development of synthetic biological tools that respond to life phenomena.