Comparison of five protein engineering strategies to stabilize an α/β-hydrolase

A review of previous stabilization of α/β-hydrolase fold enzymes revealed many different strategies, but no comparison of strategies on the same enzyme. For this reason, we compared five strategies to identify stabilizing mutations in a model α/β-hydrolase-fold enzyme, salicylic acid binding protein 2, SABP2, to reversible denaturation by urea and to irreversible denaturation by heat. The five strategies included and one location-agnostic approach (random mutagenesis using error-prone PCR), two structure-based approaches (computational design (Rosetta, FoldX) and mutation of flexible regions) and two sequence-based approaches (addition of proline at locations where a more stable homolog has proline and mutation to consensus). All strategies identified stabilizing mutations, but the best balance of success rate, degree of stabilization, and ease of implementation was mutation to consensus. A web-based automated program that predicts substitutions needed to mutate to consensus is available at http://kazlab.umn.edu .