Comparison of Genome and Plasmid-Based Engineering of Multigene Benzylglucosinolate Pathway in Saccharomyces cerevisiae.

Abstract

Intake of brassicaceous vegetables such as cabbage is associated with numerous health benefits. The major defense compounds in the Brassicales order are the amino acid-derived glucosinolates that have been associated with the health-promoting effects. This has primed a desire to build glucosinolate-producing microbial cell factories as a stable and reliable source. Here, we established-for the first time-production of the phenylalanine-derived benzylglucosinolate (BGLS) in Saccharomyces cerevisiae using two different engineering strategies: stable genome integration versus plasmid-based introduction of the biosynthetic genes. Although the plasmid-engineered strain showed a tendency to generate higher expression level of each gene (except CYP83B1) in the biosynthetic pathway, the genome-engineered strain produced 8.4-fold higher BGLS yield compared to the plasmid-engineered strain. Additionally, we optimized the genome-engineered strain by overexpressing the entry point genes CYP79A2 and CYP83B1, resulting in a 2-fold increase in BGLS production but also a 4.8-fold increase in the level of the last intermediate desulfo-benzylglucosinolate (dsBGLS). We applied several approaches to alleviate the metabolic bottleneck in the step where dsBGLS is converted to BGLS by sulfotransferase, SOT16 dependent on 3'-phosphoadenosine-5'-phosphosulfate (PAPS). BGLS production increased 1.7-fold by overexpressing SOT16 and 1.7-fold by introducing APS kinase, APK1, from Arabidopsis thaliana involved in the PAPS regeneration cycle. Modulating the endogenous sulfur assimilatory pathway through overexpression of MET3 and MET14 resulted in 2.4-fold to 12.81 μmol/L (=5.2 mg/L) for BGLS production. IMPORTANCE Intake of brassicaceous vegetables such as cabbage is associated with numerous health benefits. The major defense compounds in the Brassicales order are the amino acid-derived glucosinolates that have been associated with the health-promoting effects. This has primed a desire to build glucosinolate-producing microbial cell factories as a stable and reliable source. In this study, we engineered for the first time the production of phenylalanine-derived benzylglucosinolate in Saccharomyces cerevisiae with two engineering strategies: stable genome integration versus plasmid-based introduction of the biosynthetic genes. Although the plasmid-engineered strain generally showed higher expression level of each gene (except CYP83B1) in the biosynthetic pathway, the genome-engineered strain produced higher production level of benzylglucosinolate. Based on the genome-engineered strain, the benzylglucosinolate level was improved by optimization. Our study compared different approaches to engineer a multigene pathway for production of the plant natural product benzylglucosinolate. This may provide potential application in industrial biotechnology.