Structure-Guided Engineering of a Versatile Urethanase Improves Its Polyurethane Depolymerization Activity

Area of Science:

• Biotechnology
• Polymer Science
• Enzymology

Background:

• Polyurethane (PUR) is a major contributor to global plastic waste.
• Biotechnological approaches, particularly enzyme-based recycling, are gaining traction for plastic waste management.

Purpose of the Study:

• To elucidate the structural basis of UMG-SP2's urethanase activity.
• To engineer enhanced PUR-degrading enzymes through semi-rational design.

Main Methods:

• Determined the crystal structures of UMG-SP2 and its complexes.
• Performed molecular dynamics simulations.
• Employed semi-rational enzyme redesign.

Main Results:

• Reported the crystal structure of UMG-SP2 at 2.59 Å resolution.
• Identified flexible loop L3 as critical for hydrolytic activity.
• Developed variants (A141G, Q399A) with 30.7- and 7.4-fold increased activity on different PUR types.

Conclusions:

• Structural insights into UMG-SP2 advance the understanding of PUR-hydrolyzing enzymes.
• Engineered variants demonstrate potential for efficient industrial PUR recycling.
• These findings contribute to mitigating the environmental impact of PUR plastic waste.