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Rational, combinatorial, and genomic approaches for engineering L-tyrosine production in Escherichia coli.

ABSTRACT: Although microbial metabolic engineering has traditionally relied on rational and knowledge-driven techniques, significant improvements in strain performance can be further obtained through the use of combinatorial approaches exploiting phenotypic diversification and screening. Here, we demonstrate the combined use of global transcriptional machinery engineering and a high-throughput L-tyrosine screen towards improving L-tyrosine production in Escherichia coli. This methodology succeeded in generating three strains from two separate mutagenesis libraries (rpoA and rpoD) exhibiting up to a 114% increase in L-tyrosine titer over a rationally engineered parental strain with an already high capacity for production. Subsequent strain characterization through transcriptional analysis and whole genome sequencing allowed complete phenotype reconstruction from well-defined mutations and point to important roles for both the acid stress resistance pathway and the stringent response of E. coli in imparting this phenotype. As such, this study presents one of the first examples in which cell-wide measurements have helped to elucidate the genetic and biochemical underpinnings of an engineered cellular property, leading to the total restoration of metabolite overproduction from specific chromosomal mutations.

SUBMITTER: Santos CN

PROVIDER: S-EPMC3427108 | biostudies-literature | 2012 Aug

REPOSITORIES: biostudies-literature

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Rational, combinatorial, and genomic approaches for engineering L-tyrosine production in Escherichia coli.

Santos Christine Nicole S CN Xiao Wenhai W Stephanopoulos Gregory G

Proceedings of the National Academy of Sciences of the United States of America 20120806 34

Although microbial metabolic engineering has traditionally relied on rational and knowledge-driven techniques, significant improvements in strain performance can be further obtained through the use of combinatorial approaches exploiting phenotypic diversification and screening. Here, we demonstrate the combined use of global transcriptional machinery engineering and a high-throughput L-tyrosine screen towards improving L-tyrosine production in Escherichia coli. This methodology succeeded in gene ...[more]

PMID: 22869698

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Project description:BackgroundMulti-monocistronic and multi-variate vectors were designed, built, and tested for the improved production of cyanidin 3-O-glucoside (C3G) in Escherichia coli BL21 (DE3). The synthetic bio-parts were designed in such a way that multiple genes can be assembled using the bio-brick system, and expressed under different promoters in a single vector. The vectors harbor compatible cloning sites, so that the genes can be shuffled from one vector to another in a single step, and assembled into a single vector. The two required genes: anthocyanidin synthase (PhANS) from Petunia hybrida, and cyanidin 3-O-glucosyltransferase (At3GT) from Arabidopsis thaliana, were individually cloned under PT7, Ptrc, and PlacUV5 promoters. Both PhANS and At3GT were shuffled back and forth, so as to generate a combinatorial system for C3G production. The constructed systems were further coupled with the genes for UDP-D-glucose synthesis, all cloned in a multi-monocistronic fashion under PT7. Finally, the production of C3G was checked and confirmed using the modified M9 media, and analyzed through various chromatography and spectrometric analyses.ResultsThe engineered strains endowed with newly generated vectors and the genes for C3G biosynthesis and UDP-D-glucose synthesis were fed with 2 mM (+)-catechin and D-glucose for the production of cyanidin, and its subsequent conversion to C3G. One of the engineered strains harboring At3GT and PhANS under Ptrc promoter and UDP-D-glucose biosynthesis genes under PT7 promoter led to the production of ~?439 mg/L of C3G within 36 h of incubation, when the system was exogenously fed with 5% (w/v) D-glucose. This system did not require exogenous supplementation of UDP-D-glucose.ConclusionA synthetic vector system using different promoters has been developed and used for the synthesis of C3G in E. coli BL21 (DE3) by directing the metabolic flux towards the UDP-D-glucose. This system has the potential of generating better strains for the synthesis of valuable natural products.

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Dataset Information

Rational, combinatorial, and genomic approaches for engineering L-tyrosine production in Escherichia coli.

Publications

Rational, combinatorial, and genomic approaches for engineering L-tyrosine production in Escherichia coli.

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