Synthesis of avenanthramides using engineered Escherichia coli

Area of Science:

• Microbiology
• Biochemistry
• Metabolic Engineering

Background:

• Avenanthramides (avns) are phenolic alkaloids found in oats, known for anti-inflammatory, antioxidant, and anti-irritant properties.
• Avns are conjugates of hydroxycinnamic acids (HCs) and anthranilate derivatives.
• Genetic engineering strategies enable the synthesis of avns to explore their biological activities.

Purpose of the Study:

• To synthesize natural avenanthramides (avns) in Escherichia coli.
• To establish a microbial resource for producing diverse avns.
• To lay the groundwork for investigating the beneficial biological activities of avns.

Main Methods:

• Engineered E. coli strains to express key enzymes in the avn biosynthesis pathway, including tyrosine ammonia lyase (TAL), 4-coumarate:coenzyme A ligase (4CL), and anthranilate N-hydroxycinnamoyl/benzoyltransferase (HCBT).
• Utilized a trpD deletion mutant to enhance anthranilate precursor availability.
• Optimized fermentation conditions (temperature, cell density) for maximal avn D production.

Main Results:

• Successfully synthesized nine different avns in E. coli.
• Achieved a yield of approximately 317.2 mg/L of avn D from glucose.
• Synthesized avn E, avn F, avn A, avn G, avn B, avn C, avn H, and avn K through sequential enzymatic conversions and precursor feeding.

Conclusions:

• Demonstrated the successful microbial synthesis of nine avns, with three produced directly from glucose.
• Developed a versatile strategy for producing both natural and unnatural avns.
• Established a foundation for further exploration of the diverse biological activities of avenanthramides.