Modification of pancreatic lipase properties by directed molecular evolution

Area of Science:

• Biochemistry
• Enzymology
• Protein Engineering

Background:

• Cystic fibrosis (CF) often leads to pancreatic insufficiency.
• Acidic intraluminal conditions in CF patients reduce the efficacy of pancreatic enzyme replacement therapy (PERT), particularly lipase activity.
• Current PERT faces limitations due to suboptimal enzyme function in the gastrointestinal tract.

Purpose of the Study:

• To engineer human pancreatic lipase for enhanced activity at acidic pH.
• To improve the effectiveness of lipase-based enzyme replacement therapy for cystic fibrosis patients.
• To identify specific mutations and their effects on lipase function and substrate specificity.

Main Methods:

• Utilized directed evolution and rational design strategies to modify human pancreatic lipase.
• Developed a high-throughput screening method to identify lipase variants active at low pH.
• Employed random mutagenesis followed by sequence analysis to pinpoint beneficial mutations.

Main Results:

• A single round of mutagenesis yielded a lipase variant with approximately 50% increased activity at acidic pH on medium- and long-chain triglycerides.
• Identified two key substitutions (E179G and N406S) responsible for enhanced acidic activity and altered substrate specificity.
• Combining these mutations with K80E affected neutral pH activity but preserved acidic pH function.

Conclusions:

• The engineered lipase variant demonstrates improved performance in acidic environments, offering a potential therapeutic advantage.
• The identified mutations (E179G, N406S) are critical for modulating lipase activity and chain-length specificity at low pH.
• This study provides a foundation for designing next-generation lipase enzymes optimized for challenging gastrointestinal conditions in CF patients.