Engineering A-type Dye-Decolorizing Peroxidases by Modification of a Conserved Glutamate Residue

Area of Science:

• Biochemistry
• Enzymology
• Biotechnology

Background:

• Dye-decolorizing peroxidases (DyPs) are microbial enzymes with biotechnological applications.
• Their active site is shielded by flexible loops, with their catalytic roles not fully understood.
• A conserved glutamate in loop 2 is investigated for its role in A-type DyP function.

Purpose of the Study:

• To investigate the role of a conserved glutamate residue in loop 2 of A-type DyPs.
• To engineer DyPs with improved catalytic efficiency through site-directed mutagenesis.
• To elucidate the mechanism behind enhanced catalytic activity using computational methods.

Main Methods:

• Site saturation mutagenesis of the conserved glutamate in Bacillus subtilis DyP (BsDyP) and Kitasatospora aureofaciens DyP1 (KaDyP1).
• Screening of mutant libraries for enhanced activity against ABTS.
• Purification and characterization of selected variants for activity and stability.
• Molecular Dynamics (MD) simulations to analyze structural and dynamic changes.

Main Results:

• Identified DyP variants with significantly increased catalytic efficiency.
• MD simulations revealed improved electron channeling from surface tryptophans as the reason for enhanced activity.
• Characterization confirmed improved activity and stability in engineered variants.

Conclusions:

• The conserved glutamate residue plays a crucial role in modulating DyP activity and stability.
• Targeting this residue can engineer DyPs with superior catalytic performance for biotechnological applications.
• The glutamate may function as a pH-dependent switch, protecting the enzyme in intracellular environments.