Engineering Protein Assemblies with Stable, Selective and Reactive Metal Coordination Sites

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In this project supported by the Chemistry of Life Process Program, Prof. Akif Tezcan and his research group aim to establish design principles and experimental strategies for the construction of a new class of macrocyclic, multiprotein complexes with functional metal centers. The investigators have previously established a protein engineering strategy termed Metal-Templated Interface Redesign (MeTIR), which is inspired by the time-honored method of metal-templated, ligand synthesis. Using MeTIR, they will construct an array of oligomeric protein complexes whose stability and flexibility/rigidity can be modulated through strategically-placed, non-covalent interactions and covalent linkages. These complexes are designed to serve as tunable macrocyclic metal ligands, which will allow the examination of fundamental relationships between scaffold rigidity and the stability and selectivity of metal binding as well as the construction of interfacial binding sites for catalytically-active metal centers. The catalytic activity of these synthetic metalloprotein assemblies toward several model hydrolysis reactions will be measured. Computationally-guided, active site-directed mutagenesis will be employed in an effort to improve the catalytic efficiency of the artificial metalloenzymes. The proposed research will explore the viability and scope of proteins as building blocks for coordination chemistry with the ultimate aim of providing clues on how nature has evolved proteins to utilize and harness metal reactivity. Proteins are nature's premier building blocks for the construction of metalloenzymes that can be viewed as complex biological devices or as coordination complexes with diverse metal-based functions. Yet, the pursuit of the assembly of proteins or their use as synthetic building blocks for inorganic coordination chemistry has been limited. The investigation requires use of a wide array of technical skills in coordination chemistry, molecular biology, protein biochemistry, crystallography, and biophysics. Hence the graduate, undergraduate, and high school students involved in the proposed research will gain a broad and interdisciplinary training. The principal investigator will continue outreach efforts by recruiting members of groups underrepresented in science through various self-initiated and campus-supported programs and by participating in science fairs at local elementary schools.