Rational design of a Yarrowia lipolytica derived lipase for improved thermostability

To improve the thermostability of the lipase LIP2 from Yarrowia lipolytica, molecular dynamics (MD) simulations at various temperatures were used to investigate the common fluctuation sites of the protein, which are considered to be thermally weak points. Two of these residues were selected for mutations to improve the enzyme's thermostability, and the variants predicted by MD simulations to have improved thermostability were expressed in Pichia pastoris GS115 for further investigations. According to the proline rule, the high fluctuation site S115 or V213 was replaced with proline residue, the two lipase mutants S115P and V213P were obtained. The mutant V213P exhibited evidently enhanced thermostability with an approximately 70% longer half-life at 50 °C than that of the parent LIP2 expressed in P. pastoris. The temperature optimum of V213P was 42 °C, which was about 5.0 °C higher than that of the parent LIP2, while its specific catalytic activity was comparable to that of the parent and reached 876.5 U/mg. The improved thermostability of V213P together with its high catalytic efficiency indicated that the rational design strategy employed here can be efficiently applied for structure optimization of industrially important enzymes.