Enhancing Thermostability of Bacillus licheniformis Lipase with LEA Peptide Co-expression System.

Abstract

Heterozygous protein expression in E. coli facilitates high yield and quality. However, the challenges of protein instability due to environmental stress are still an issue that affects the activity of the protein produced. In this study, the improvement of protein thermostability was done using a peptide co-expression system. The developed system exploited the usefulness of Late Abundant Embryogenesis (LEA) proteins to protect proteins from damage. Recombinant lipase from Bacillus licheniformis was expressed along with the LEA-like peptide, whose design was inspired by the 11 repetitive amino acid sequences of the LEA protein. In total, four LEA-like peptide co-expression systems were assessed. The evaluation of improvements in protein thermostability was conducted using a standard lipase assay. The purified lipase was challenged at 45 °C, a higher temperature than its optimal temperature. Two-fold lipase activity was recorded from the protein co-expressed with the LEA-II-like peptide. Based on amino acid sequence comparison, LEA-II has the advantage of containing more polar residues with several aliphatic amino acids, which may improve LipA_{B.licheniformis}-LEA II complex stability at higher temperatures. Next, molecular docking and molecular dynamic simulation were employed to analyze the stability of the lipase in the presence and absence of LEA II. The findings of the RMSD, MM-GBSA and related analyses showed that the LipA_{B.licheniformis}-LEA II complexes have better stability than the LipA_{B.licheniformis} alone, thus supporting the lipase assay. These findings successfully unravel the potential of the LEA-like peptide co-expression system as a novel approach to improve enzyme thermostability.