Corporate Banner
Satellite Banner
Metabolomics & Lipidomics
Scientific Community
Become a Member | Sign in
Home>News>This Article

Less Toxic Metabolites, More Chemical Product

Published: Thursday, October 31, 2013
Last Updated: Thursday, October 31, 2013
Bookmark and Share
The first dynamic regulatory system that prevents the build-up of toxic metabolites in engineered microbes has been reported.

The JBEI researchers used their system to double the production in Escherichia coli (E. coli) of amorphadiene, a precursor to the premier antimalarial drug artemisinin.

Using genome-wide transcriptional analysis, the JBEI researchers identified native regions of DNA – called “promoters” – in E. coli that respond to toxic metabolites by promoting the expression of protective genes. They then developed a system based on these promoters for regulating artificial metabolic pathways engineered into the E.coli to enable the bacterium to produce amorphadiene.

“Static regulators of toxic metabolite levels have been developed but this is the first metabolite regulator that responds to changes in microbial growth and environmental conditions,” says Jay Keasling, CEO of JBEI and ranking authority on synthetic biology, who led this research. “Control systems that can sense and respond to environmental or growth changes are needed for the optimal production of a desired chemical.”

Keasling, who also serves as Associate Laboratory Director of Biosciences at Lawrence Berkeley National Laboratory (Berkeley Lab), the lead institute in the JBEI partnership, is the corresponding author of a paper describing this research in the journal Nature Biotechnology. The paper is titled “Engineering dynamic pathway regulation using stress-response promoters.” Co-authors are Robert Dahl, Fuzhong Zhang, Jorge Alonso-Gutierrez, Edward Baidoo, Tanveer Batth, Alyssa  Redding-Johanson, Christopher Petzold, Aindrila Mukhopadhyay, Taek Soon Lee and Paul Adams.

From life-saving drugs, such as artemisinin, to sustainable, green biofuels, the metabolic engineering of microbes for the production of valuable chemicals continues to grow in importance. To date, the most productive microbial hosts have been those engineered with heterologous pathways for which they have little or no native regulation of the metabolites being expressed. However, such unregulated expression of heterologous enzymes can be toxic to the host, which can limit the production of the target chemical to well below levels that could be obtained.

“Although synthetic biology has made great strides in creating novel, dynamic genetic circuits, most control systems for heterologous metabolic pathways still rely on inducible or constitutive promoters,” Keasling says. “Approaches developed to tailor expression strength by means of promoter libraries, mRNA stability or ribosome-binding are optimized for a particular growth phase or condition in the bioreactor, however, growth and environmental conditions change during the fermentation process.”

Since the accumulation of intermediate metabolites to toxic levels in a microbe during a fermentation process can lead to a stress response, Keasling and his JBEI colleagues reasoned that it should be possible to tap a host microbe’s native stress response system when metabolites accumulate. Transcript profiling of the E.coli genome allowed them to evaluate  transcriptional response to a heterologous pathway and create a list of promoters that could be used to respond to intermediate toxicity.

“Using such promoters to regulate pathway expression in response to the toxic intermediate metabolites creates a link between the cell’s metabolic state and the expression of the metabolic pathway,” Keasling says. “This enables us to create biosensors that respond to and regulate pathway intermediates. In silico models have indicated, and we’ve demonstrated in this study that our approach can be used to improve production of a desired chemical over common inducible promoters and constitutive promoters of various strengths.”

Keasling and his colleagues believe their dynamic approach to metabolite regulation could be extended to higher organisms as well, where constitutive promot¬ers are still commonly used. This holds potential for – among other things – improving the accumulation of nutrients in food crops, or decreasing the lignin in energy crops that makes extraction of fuel sugars difficult and expensive.

“What we’re looking at are strategies that could help reduce the problems associated with feeding a larger global population or efficiently converting biomass into renewable fuels,” Keasling says.

Further Information
Access to this exclusive content is for Technology Networks Premium members only.

Join Technology Networks Premium for free access to:

  • Exclusive articles
  • Presentations from international conferences
  • Over 2,600+ scientific posters on ePosters
  • More than 3,800+ scientific videos on LabTube
  • 35 community eNewsletters

Sign In

Forgotten your details? Click Here
If you are not a member you can join here

*Please note: By logging into you agree to accept the use of cookies. To find out more about the cookies we use and how to delete them, see our privacy policy.

Related Content

Dirty,Crusty Meals Fit for (Long-Dormant) Microbes
Researchers apply the latest analytical techniques to further our understanding of desert biocrusts.
Wednesday, September 23, 2015
Scientific News
How Cell Growth Triggers Cell Division
Researchers in Jan Skotheim's lab have discovered a previously unknown mechanism that controls how large cells grow, an insight that could one day provide insight into attacking diseases such as cancer.
Metabolomic Platform Reveals Fundamental Flaw in Common Lab Technology
A new study led by scientists at The Scripps Research Institute (TSRI) shows that a technology used in thousands of laboratories, called gas chromatography mass spectrometry (GC-MS), fundamentally alters the samples it analyzes.
Newly Identified Biochemical Pathway Could Be Target for Insulin Control
Researchers at Duke Medicine and the University of Alberta are reporting the identification of a new biochemical pathway to control insulin secretion from islet beta cells in the pancreas, establishing a potential target for insulin control.
Dirty,Crusty Meals Fit for (Long-Dormant) Microbes
Researchers apply the latest analytical techniques to further our understanding of desert biocrusts.
CSI -- On The Metabolite's Trail
Bioinformaticians at the University of Jena make the most efficient search engine for molecular structures available online.
Developing a Breathalyzer-Type Low Blood Sugar Warning Device For Diabetes
A multidisciplinary team of researchers at Indiana University-Purdue University Indianapolis has been awarded a $738,000 National Science Foundation grant to develop a breathalyzer-type device to detect the onset of hypoglycemia, or low blood sugar episodes, in people with diabetes.
Identifying The 'Dimmer Switch' Of Diabetes
University of Alberta research gives new insight into what causes Type 2 diabetes.
10 to 1: Bugs Win in NASA study
Bugs are winning out, and that's a good thing according to NASA's Human Research Program.
MYC Oncogene Disrupts Cancers Rhythm
Findings inform time-dependent treatment for reducing side effects and increasing effectiveness of cancer medications.
Keeping Gut Bacteria in Balance Could Help Delay Age-related Diseases
A new study suggests that analyzing intestinal bacteria could be a promising way to predict health outcomes as we age.
Skyscraper Banner

Skyscraper Banner
Go to LabTube
Go to eposters
Access to the latest scientific news
Exclusive articles
Upload and share your posters on ePosters
Latest presentations and webinars
View a library of 1,800+ scientific and medical posters
2,600+ scientific and medical posters
A library of 2,500+ scientific videos on LabTube
3,800+ scientific videos