How to Engineer Organic Solvent Resistant Enzymes: Insights from Combined Molecular Dynamics and Directed Evolution Study

Expanding synthetic capabilities to routinely employ enzymes in organic solvents (OSs) is a dream for protein engineers and synthetic chemists. Despite significant advances in the field of protein engineering, general and transferable design principles to improve the OS resistance of enzymes are poorly understood. Herein, we report a combined computational and directed evolution study of Bacillus subtlis lipase A (BSLA) in three OSs (i. e., 1,4‐dioxane, dimethyl sulfoxide, 2,2,2‐trifluoroethanol) to devise a rational strategy to guide engineering OS resistant enzymes. Molecular dynamics simulations showed that OSs reduce BSLA activity and resistance in OSs by (i) stripping off essential water molecules from the BLSA surface mainly through H‐bonds binding; and (ii) penetrating the substrate binding cleft leading to inhibition and conformational change. Interestingly, integration of computational results with “BSLA‐SSM” variant library (3439 variants; all natural diversity with amino acid exchange) revealed two complementary rational design strategies: (i) surface charge engineering, and (ii) substrate binding cleft engineering. These strategies are most likely applicable to stabilize other lipases and enzymes and assist experimentalists to design organic solvent resistant enzymes with reduced time and screening effort in lab experiments. Stay positive: Surface charge engineering (introduction of positively charged substitutions) and substrate binding cleft non‐polar engineering strategies could serve as general rational protein engineering principles to stabilize lipases in OSs and might apply to other enzymes sharing a similar α/β‐hydrolase fold.