Artificial Protein Assemblies Induced by Metal Coordination Interaction

摘要

In biological systems, many protein assemblies are ubiquitous and play various, complicated and important roles. Most of such assemblies are achieved with electrostatic, hydrophobic and hydrogen bonding interactions. However, in the artificial assembling systems, these interactions may cause difficulties to control nonspecific protein aggregates. In contrast, the well-defined protein assembly by the interprotein metal coordination with amino acids has been demonstrated by Tezcan and his group. They have focused on the cytochrome cb_(562), a stable monomeric hemoprotein with covalently linked c-type heme, as a building block and introduced some histidines, ligands of a metal ion, on the interacting a-helices in the packing structure of protein crystals. Two constructed bis-His motifs were found to bind the zinc ion to afford the dimer and tetramer in the solution. In addition, this tetramer was characterized by X-ray crystal structure to reveal the D_(2)-symmetrical topology. Further investigation demonstrated the metal dependent structural changes and stabilization of tetramer by introduction of suitable hydrophobic residues. This approach for highly-defined protein assemblies will contribute the development of new-type of bionanomaterials.