Engineering of Thermomyces lanuginosus lipase Lip: creation of novel biocatalyst for efficient biosynthesis of chiral intermediate of Pregabalin.

Efficient and highly enantioselective hydrolysis of 2-carboxyethyl-3-cyano-5-methylhexanoic acid ethyl ester (CNDE) is the most crucial step in chemoenzymatic synthesis of Pregabalin. By using site-saturation mutagenesis and high-throughput screening techniques, lipase Lip from Thermomyces lanuginosus DSM 10635 was engineered to improve its activity towards CNDE. The triple mutant, S88T/A99N/V116D exhibited a 60-fold improvement in specific activity for CNDE (2.35 U/mg) over the wild-type Lip (0.039 U/mg). Modeling and docking studies demonstrated that the mutant could more effectively stabilize oxygen anions in transition states and the lid of Lip in the open conformation. Additionally, the kinetic resolution of CNDE catalyzed by Escherichia coli cell overexpressing S88T/A99N/V116D mutant afforded (3S)-2-carboxyethyl-3-cyano-5-methylhexanoic acid in 42.4 % conversion and 98 % ee within 20 h with a substrate loading of 1 M (255 g/l). These results demonstrated that a novel and promising biocatalyst was created for efficient chemoenzymatic manufacturing of Pregabalin.

Transcriptomic and Metabolomic Analyses Provide Insights into the Formation of the Peach-like Aroma of Fragaria nilgerrensis Schlecht. Fruits.

Fragaria nilgerrensis Schlecht. is a wild diploid strawberry species. The intense peach-like aroma of its fruits makes F. nilgerrensis an excellent resource for strawberry breeding programs aimed at enhancing flavors. However, the formation of the peach-like aroma of strawberry fruits has not been comprehensively characterized. In this study, fruit metabolome and transcriptome datasets for F. nilgerrensis (HA; peach-like aroma) and its interspecific hybrids PA (peach-like aroma) and NA (no peach-like aroma; control) were compared. In total, 150 differentially accumulated metabolites were detected. The K-means analysis revealed that esters/lactones, including acetic acid, octyl ester, δ-octalactone, and δ-decalactone, were more abundant in HA and PA than in NA. These metabolites may be important for the formation of the peach-like aroma of F. nilgerrensis fruits. The significantly enriched gene ontology terms assigned to the differentially expressed genes (DEGs) were fatty acid metabolic process and fatty acid biosynthetic process. Twenty-seven DEGs were predicted to be associated with ester and lactone biosynthesis, including AAT, LOX, AOS, FAD, AIM1, EH, FAH, ADH, and cytochrome P450 subfamily genes. Thirty-five transcription factor genes were predicted to be associated with aroma formation, including bHLH, MYB, bZIP, NAC, AP2, GATA, and TCPfamily members. Moreover, we identified differentially expressed FAD, AOS, and cytochrome P450 family genes and NAC, MYB, and AP2 transcription factor genes that were correlated with δ-octalactone and δ-decalactone. These findings provide key insights into the formation of the peach-like aroma of F. nilgerrensis fruits, with implications for the increased use of wild strawberry resources.

Key residues responsible for enhancement of catalytic efficiency of Thermomyces lanuginosus lipase Lip revealed by complementary protein engineering strategy.

The variant Lip-T (S88T/A99N/V116D) of lipase Lip from Thermomyces lanuginosus has been proved to be a potential biocatalyst for kinetic resolution of 2-carboxyethyl-3-cyano-5-methylhexanoic acid ethyl ester (CNDE) to produce valuable chiral intermediate of Pregabalin. In this study, random, site-directed and site-saturation mutagenesis were performed to further enhance the activity of Lip-T, and the key residues responsible for catalytic efficiency were revealed. A mutant S63L/D232A with improved activity toward CNDE was obtained after screening of approximately 2500 clones from random-mutant libraries. Site-directed mutagenesis at site 63 and 232 demonstrated that the single-point mutants S63L and D232A showed opposite effect on activity. S63L exhibited a significant improvement on activity, whereas D232A exerted a slight inhibitory effect. Then a mutant S63M with a 4.5-fold higher catalytic efficiency than Lip-T was obtained by site-saturation mutagenesis. Structural changes resulting from the mutations were analyzed and the mechanisms responsible for the enhanced activity were discussed. Moreover, the engineered lipase catalyzed enantioselective hydrolysis of CNDE at a very high substrate loading (765 g/l). As only 5% (w/v) resting cells were used, the bioprocess is much more cost-effective than Pfizer's process using 8% (w/v) commercially available lipase Lipolase(®). These results provide not only new insights into lipase structure-function relationships but also a novel robust biocatalyst for the production of Pregabalin.