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Balancing a heterologous mevalonate pathway for improved isoprenoid production in Escherichia coli

Paper ID Volume ID Publish Year Pages File Format Full-Text
32000 44872 2007 15 PDF Available
Title
Balancing a heterologous mevalonate pathway for improved isoprenoid production in Escherichia coli
Abstract

Engineering biosynthetic pathways in microbes for the production of complex chemicals and pharmaceuticals is an attractive alternative to chemical synthesis. However, in transferring large pathways to alternate hosts and manipulating expression levels, the native regulation of carbon flux through the pathway may be lost leading to imbalances in the pathways. Previously, Escherichia coli was engineered to produce large quantities of isoprenoids by creating a mevalonate-based isopentenyl pyrophosphate biosynthetic pathway [Martin, V.J., Pitera, D.J., Withers, S.T., Newman, J.D., Keasling, J.D., 2003. Engineering a mevalonate pathway in Escherichia coli for production of terpenoids. Nat. Biotechnol. 21, 796–802]. The strain produces high levels of isoprenoids, but upon further investigation we discovered that the accumulation of pathway intermediates limited flux and that high-level expression of the mevalonate pathway enzymes inhibited cell growth. Gene titration studies and metabolite profiling using liquid chromatography–mass spectrometry linked the growth inhibition phenotype with the accumulation of the pathway intermediate 3-hydroxy-3-methyl-glutaryl-coenzyme A (HMG-CoA). Such an accumulation implies that the activity of HMG-CoA reductase was insufficient to balance flux in the engineered pathway. By modulating HMG-CoA reductase production, we eliminated the pathway bottleneck and increased mevalonate production. These results demonstrate that balancing carbon flux through the heterologous pathway is a key determinant in optimizing isoprenoid biosynthesis in microbial hosts.

Keywords
Pathway engineering; Isoprenoids; Toxicity; Mevalonate pathway; E. coli
First Page Preview
Balancing a heterologous mevalonate pathway for improved isoprenoid production in Escherichia coli
Publisher
Database: Elsevier - ScienceDirect
Journal: Metabolic Engineering - Volume 9, Issue 2, March 2007, Pages 193–207
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering