Engineering 7β-Hydroxysteroid Dehydrogenase for Enhanced Ursodeoxycholic Acid Production by Multiobjective Directed...

Area of Science:

• Biotechnology
• Enzyme Engineering
• Biocatalysis

Background:

• Ursodeoxycholic acid (UDCA) is a key pharmaceutical compound derived from bile.
• 7β-Hydroxysteroid dehydrogenase (HSDH) is crucial for UDCA synthesis but exhibits limitations in activity and stability.
• Existing HSDH enzymes hinder efficient and scalable UDCA production.

Purpose of the Study:

• To improve the activity, thermostability, and pH profile of 7β-HSDH.
• To enhance the overall efficiency of UDCA bioproduction.
• To develop a robust enzyme for industrial applications.

Main Methods:

• Multiobjective directed evolution (MODE) was employed to engineer 7β-HSDH.
• The enzyme variant V3-1 was selected based on improved catalytic properties.
• Performance was evaluated in a cascade reaction for UDCA synthesis.

Main Results:

• The best variant (V3-1) exhibited a 5.5-fold increase in specific activity and a 3-fold longer half-life compared to the wild type.
• The variant's optimal pH shifted to a weakly alkaline range.
• UDCA production reached 942 g L⁻¹ day⁻¹ with V3-1, a substantial improvement over the wild type's 141 g L⁻¹ day⁻¹.

Conclusions:

• The MODE strategy successfully enhanced 7β-HSDH performance.
• The engineered enzyme significantly boosts UDCA bioproduction efficiency.
• This work offers a valuable approach for enzyme improvement in biocatalysis.