structural insights into the evolution of a non-biological protein importance of surface residues in protein fold optimization结构洞察的进化生物蛋白质表面残留的蛋白质折叠优化的重要性.pdf

Structural Insights into the Evolution of a Non-Biological Protein: Importance of Surface Residues in Protein Fold Optimization 1,2 1,2 2 2 3 1,2 Matthew D. Smith , Matthew A. Rosenow , Meitian Wang , James P. Allen , Jack W. Szostak , John C. Chaput * 1 Center for BioOptical Nanotechnology, The Biodesign Institute, Arizona State University, Tempe, Arizona, United States of America, 2 Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona, United States of America, 3 Howard Hughes Medical Institute, Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, United States of America Phylogenetic profiling of amino acid substitution patterns in proteins has led many to conclude that most structural information is carried by interior core residues that are solvent inaccessible. This conclusion is based on the observation that buried residues generally tolerate only conserved sequence changes, while surface residues allow more diverse chemical substitutions. This notion is now changing as it has become apparent that both core and surface residues play important roles in protein folding and stability. Unfortunately, the ability to identify specific mutations that will lead to enhanced stability remains a challenging problem. Here we discuss two mutations that emerged from an in vitro selection experiment designed to improve the folding stability of a non-biological ATP binding protein. These mutations alter two solvent accessible residues, and dramatically enhance the expression, solubility, thermal stability, and ligand binding affinity of the protein. The significance of both mutations was investigated individually and together, and