Controlling the metabolic flux through the carotenoid pathway using directed mRNA processing and stabilization

Area of Science:

• Metabolic Engineering
• Synthetic Biology
• Biochemistry

Background:

• Carotenoids are vital pigments with diverse applications.
• Efficiently producing specific carotenoids like beta-carotene requires precise control over metabolic pathways.
• The carotenoid pathway involves multiple enzymatic steps, making it a target for metabolic engineering.

Purpose of the Study:

• To engineer a synthetic operon for coordinated gene regulation within the carotenoid pathway.
• To modulate the flux through the carotenoid pathway by controlling gene expression levels.
• To investigate the impact of enzyme levels on pathway intermediate accumulation.

Main Methods:

• Constructed a synthetic operon with crtI and crtY genes under the araBAD promoter in E. coli.
• Incorporated mRNA secondary structures and an RNase E site to regulate gene expression.
• Varied mRNA structures to control enzyme levels and pathway flux.
• Analyzed carotenoid production (beta-carotene, lycopene) and pathway intermediates.

Main Results:

• Achieved a 300-fold variation in beta-carotene to lycopene production by modulating mRNA secondary structures.
• Observed novel pathway intermediates not seen with the standard recombinant operon.
• Demonstrated that enzyme levels directly influence the formation of metabolic intermediates.

Conclusions:

• Coordinated regulation of metabolic pathway genes is achievable using synthetic operons.
• Modulating enzyme levels via mRNA structures effectively balances flux and intermediate production.
• This approach offers a powerful tool for optimizing the biosynthesis of valuable compounds.