Evolution of E. coli Phytase for Increased Thermostability Guided by Rational Parameters

Area of Science:

• Biotechnology
• Enzyme Engineering
• Biocatalysis

Background:

• Phytases hydrolyze phytate, increasing nutrient availability and reducing environmental pollution.
• Low thermostability of current phytases limits their use in industrial processes like feed pelletization.

Purpose of the Study:

• To enhance the heat stability of *Escherichia coli* phytase through rational protein engineering.
• To develop a more efficient method for creating thermostable phytases for industrial applications.

Main Methods:

• Utilized B-value calculation and protein surface engineering to identify key amino acid residues for mutation.
• Constructed mutant libraries based on identified mutation sites and performed iterative screening.
• Employed structural analysis of histidine acid phosphatase homologs (models 1DKL and 1DKQ).

Main Results:

• Successfully engineered a thermophilic phytase mutant, P56214, after five rounds of screening.
• The P56214 mutant retained 75% enzyme activity after 5 min at 90°C, a significant increase from the wild-type's 20%.
• The rational engineering approach reduced screening workload compared to traditional methods.

Conclusions:

• Rational protein engineering is an effective strategy for improving phytase thermostability.
• The developed thermophilic phytase mutant has potential for broader industrial applications, particularly in feed processing.
• This study provides a valuable reference for developing green catalysts through enzyme engineering.