Computational Design of Phosphotriesterase Improves V-Agent Degradation Efficiency

Area of Science:

• Biochemistry
• Enzyme Engineering
• Toxicology

Background:

• Organophosphates (OPs) are potent neurotoxins that inhibit acetylcholinesterase, posing significant health risks.
• Current treatments for OP poisoning are limited in efficacy.
• Enzymatic scavengers offer a potential strategy for systemic degradation of OPs.

Purpose of the Study:

• To computationally design and characterize variants of phosphotriesterase (PTE) for enhanced degradation of organophosphates.
• To identify specific mutations that improve PTE's catalytic efficiency against OP nerve agents like VX and VR.
• To understand the structure-function relationships of key residues in PTE for OP hydrolysis.

Main Methods:

• Computational design of phosphotriesterase (PTE) variants.
• Site-directed mutagenesis to introduce specific amino acid substitutions.
• Enzymatic assays to measure the catalytic efficiency of PTE variants against organophosphates (VX and VR).
• Structural analysis to assess the impact of mutations on enzyme integrity.

Main Results:

• Several computationally designed PTE variants, including those with mutations G208D, F104A, K77A, A80V, H254G, and I274N, demonstrated broadly improved catalytic efficiency for VX and VR hydrolysis.
• The mutation I106A specifically enhanced VR hydrolysis.
• The mutation L271E abolished PTE activity, likely due to structural destabilization.
• Mutations did not significantly impact the overall enzyme structure.

Conclusions:

• Computationally designed mutations can significantly enhance the catalytic efficiency of phosphotriesterase for organophosphate degradation.
• Specific residues play critical roles in PTE's activity and structural stability.
• These findings contribute to the development of novel enzymatic scavengers for treating organophosphate toxicity.