Reduced peroxisomal citrate synthase activity increases substrate availability for polyhydroxyalkanoate biosynthesis...

Area of Science:

• Metabolic Engineering
• Plant Biotechnology
• Biopolymer Production

Background:

• Polyhydroxyalkanoates (PHAs) are biodegradable plastics produced by bacteria, offering a renewable alternative to petroleum-based plastics.
• Plant-based PHA production is being explored to reduce industrial manufacturing costs and environmental impact.
• Previous studies showed promising peroxisomal PHA accumulation in sugarcane, but higher yields are needed for commercial viability.

Purpose of the Study:

• To investigate strategies for increasing polyhydroxybutyrate (PHB) accumulation in plants.
• To identify metabolic bottlenecks limiting peroxisomal PHA biosynthesis in plants.
• To evaluate the potential of reducing peroxisomal citrate synthase activity for enhanced PHA production.

Main Methods:

• Exogenous fatty acid feeding of Arabidopsis thaliana engineered with peroxisome-targeted PHA synthesis enzymes (PhaA, PhaB, PhaC) from Cupriavidus necator.
• Metabolic analysis to assess substrate availability from the β-oxidation cycle.
• Artificial microRNA-mediated knockdown of peroxisomal citrate synthase activity.

Main Results:

• Substrate availability from the β-oxidation cycle was identified as a limiting factor for peroxisomal PHB biosynthesis.
• Knockdown of peroxisomal citrate synthase activity led to a threefold increase in PHB production levels.
• This demonstrates that manipulating this pathway can significantly enhance PHA accumulation.

Conclusions:

• The availability of β-oxidation cycle intermediates is crucial for efficient peroxisomal PHA production in plants.
• Reducing peroxisomal citrate synthase activity is a viable metabolic engineering strategy to boost PHA yields.
• This approach holds promise for increasing plant-based PHA production in various crop species for commercial applications.