Altered Carbon Partitioning Enhances CO₂ to Terpene Conversion in Cyanobacteria.

Area of Science:

• Metabolic Engineering
• Synthetic Biology
• Biotechnology

Background:

• Photosynthetic terpene production offers an efficient CO2 conversion route.
• Enhancing terpene yield in photosynthetic organisms is challenging due to low carbon partitioning.
• Competition exists between primary metabolism and terpene biosynthesis.

Purpose of the Study:

• To investigate carbon partitioning in Synechococcus elongatus PCC 7942.
• To engineer metabolic pathways for enhanced terpene production.
• To improve limonene yield through systems biology and enzyme engineering.

Main Methods:

• Systems biology analysis to identify carbon competition.
• Metabolic engineering by knocking out sucrose or glycogen biosynthesis.
• Enzyme engineering using a fusion complex of geranyl diphosphate synthase (GPPS) and limonene synthase (LS).

Main Results:

• Identified strong carbon competition between primary metabolism and terpene biosynthesis.
• Successfully enhanced limonene production by altering carbon partitioning through knockout strategies.
• Achieved a limonene titer of 21.0 mg/L by combining source and sink pathway engineering.

Conclusions:

• Balancing carbon flux between primary and secondary metabolism is key for enhancing terpene bioproduction in cyanobacteria.
• Synergistic engineering of carbon sources and sinks significantly improves natural product yield.
• This approach holds potential for improving yields of various natural products in photosynthetic species.