earticle

영어

Current metabolic engineering studies are limited by the ability to finely and predictively express pathway enzymes and to screen superior and optimized variant from vast library. Here, we present an integrated approach which settled above problems to produce L-tryptophan from Escherichia coli. First, we removed known bottlenecks on L-tryptophan synthesis pathway by using a predictive model of protein expression level, UTR Designer, which can precisely predict expression level of enzyme based on folding energy of specific features in mRNA secondary structure. UTR sequences of bottleneck enzymes were re-designed to maximize the metabolic flux through the pathway. Then we optimized the producing strain by using a riboswitch-based screening tool called riboselector, which modulates expression level of selective marker gene in response to the target molecule. Riboselector for L-tryptophan was able to enrich superior variants out of vast library which were constructed from rationally engineered strain. We claim here that high-performance producing strains could be obtained through the integrated approach by resolving pre-existing problems of metabolic engineering.