Designing Efficient Enzymes: Eight Predicted Mutations Convert a Hydroxynitrile Lyase into an Efficient Esterase.

Hydroxynitrile lyase from rubber tree (HNL) shares 45% identical amino acid residues with the homologous esterase from tobacco, SABP2, but the two enzymes catalyze different reactions. The x-ray structures reveal a serine-histidine-aspartate catalytic triad in both enzymes along with several differing amino acid residues within the active site. Previous exchange of three amino acid residues in the active site of HNL with the corresponding amino acid residue in SABP2 (T11G-E79H-K236M) created variant HNL3, which showed low esterase activity toward p-nitrophenyl acetate.

Comparison of Five Protein Engineering Strategies for Stabilizing an α/β-Hydrolase.

A review of the 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, to reversible denaturation by urea and to irreversible denaturation by heat. The five strategies included one location agnostic approach (random mutagenesis using error-prone polymerase chain reaction), 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 homologue has proline and mutation to consensus).