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Systems analysis of methylerythritol-phosphate pathway flux in E. coli: insights into the role of oxidative stress and the validity of lycopene as an isoprenoid reporter metabolite

Overview of attention for article published in Microbial Cell Factories, November 2015
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Title
Systems analysis of methylerythritol-phosphate pathway flux in E. coli: insights into the role of oxidative stress and the validity of lycopene as an isoprenoid reporter metabolite
Published in
Microbial Cell Factories, November 2015
DOI 10.1186/s12934-015-0381-7
Pubmed ID
Authors

Mareike Bongers, Panagiotis K. Chrysanthopoulos, James B. Y. H. Behrendorff, Mark P. Hodson, Claudia E. Vickers, Lars K. Nielsen

Abstract

High-throughput screening methods assume that the output measured is representative of changes in metabolic flux toward the desired product and is not affected by secondary phenotypes. However, metabolic engineering can result in unintended phenotypes that may go unnoticed in initial screening. The red pigment lycopene, a carotenoid with antioxidant properties, has been used as a reporter of isoprenoid pathway flux in metabolic engineering for over a decade. Lycopene production is known to vary between wild-type Escherichia coli hosts, but the reasons behind this variation have never been fully elucidated. In an examination of six E. coli strains we observed that strains also differ in their capacity for increased lycopene production in response to metabolic engineering. A combination of genetic complementation, quantitative SWATH proteomics, and biochemical analysis in closely-related strains was used to examine the mechanistic reasons for variation in lycopene accumulation. This study revealed that rpoS, a gene previously identified in lycopene production association studies, exerts its effect on lycopene accumulation not through modulation of pathway flux, but through alteration of cellular oxidative status. Specifically, absence of rpoS results in increased accumulation of reactive oxygen species during late log and stationary phases. This change in cellular redox has no effect on isoprenoid pathway flux, despite the presence of oxygen-sensitive iron-sulphur cluster enzymes and the heavy redox requirements of the methylerythritol phosphate pathway. Instead, decreased cellular lycopene in the ΔrpoS strain is caused by degradation of lycopene in the presence of excess reactive oxygen species. Our results demonstrate that lycopene is not a reliable indicator of isoprenoid pathway flux in the presence of oxidative stress, and suggest that caution should be exercised when using lycopene as a screening tool in genome-wide metabolic engineering studies. More extensive use of systems biology for strain analysis will help elucidate such unpredictable side-effects in metabolic engineering projects.

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Mendeley readers

The data shown below were compiled from readership statistics for 54 Mendeley readers of this research output. Click here to see the associated Mendeley record.

Geographical breakdown

Country Count As %
United States 1 2%
China 1 2%
France 1 2%
Unknown 51 94%

Demographic breakdown

Readers by professional status Count As %
Researcher 22 41%
Student > Ph. D. Student 12 22%
Student > Master 8 15%
Student > Postgraduate 3 6%
Professor 1 2%
Other 3 6%
Unknown 5 9%
Readers by discipline Count As %
Agricultural and Biological Sciences 22 41%
Biochemistry, Genetics and Molecular Biology 13 24%
Chemistry 5 9%
Engineering 2 4%
Business, Management and Accounting 1 2%
Other 5 9%
Unknown 6 11%

Attention Score in Context

This research output has an Altmetric Attention Score of 1. This is our high-level measure of the quality and quantity of online attention that it has received. This Attention Score, as well as the ranking and number of research outputs shown below, was calculated when the research output was last mentioned on 02 December 2015.
All research outputs
#10,504,583
of 13,181,559 outputs
Outputs from Microbial Cell Factories
#686
of 959 outputs
Outputs of similar age
#241,110
of 354,535 outputs
Outputs of similar age from Microbial Cell Factories
#72
of 121 outputs
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