Remodeling enzyme active sites by stepwise loop insertion.

Area of Science:

• Enzyme engineering and protein evolution
• Structural biology and bioinformatics
• Biocatalysis and synthetic biology

Background:

• Remolding active site loops is crucial for enzyme divergent evolution.
• Direct residue insertion in active site loops can compromise protein structure and function.

Purpose of the Study:

• To design a robust strategy for enzyme active site engineering.
• To overcome limitations of traditional residue insertion methods.
• To evolve novel enzyme catalytic properties and substrate specificities.

Main Methods:

• Developed the stepwise loop insertion strategy (StLois).
• Involves stepwise introduction of randomized residue pairs using NNK codon degeneracy.
• Utilizes structural and functional analysis for target region identification and iterative mutagenesis.

Main Results:

• Successfully evolved the substrate preference of a lactonase to that of a phosphotriesterase.
• Demonstrated efficient expansion of residues in loop regions.
• Successfully remodeled enzyme active site architecture.

Conclusions:

• The StLois method provides an efficient approach for enzyme active site engineering.
• Enables expansion of loop regions and remodeling of active site architecture for novel functions.
• Facilitates the evolution of enzymes with altered substrate preferences and catalytic properties.