A mutant phospholipase D with enhanced thermostability from Streptomyces sp

Area of Science:

• Biochemistry
• Enzymology
• Protein Engineering

Background:

• Phospholipase D (PLD) enzymes are crucial in cellular signaling and lipid metabolism.
• Understanding the factors contributing to enzyme thermostability is vital for industrial applications and protein engineering.
• Existing research highlights variations in PLD thermostability among different microbial sources.

Purpose of the Study:

• To elucidate the role of specific amino acid residues in determining the thermostability of Streptomyces phospholipase D (PLD).
• To engineer a more thermostable variant of PLD through targeted mutagenesis.

Main Methods:

• Construction of a chimeric PLD by recombining regions of a thermolabile (K1PLD) and a thermostable (TH-2PLD) variant.
• Identification of candidate thermostability-related amino acid residues through comparative primary structure analysis.
• Site-directed mutagenesis to introduce specific amino acid substitutions, notably Glu346Asp in K1PLD.

Main Results:

• The chimeric K/T/KPLD construct exhibited intermediate thermostability between the parent enzymes.
• Comparative analysis identified seven candidate amino acid residues influencing PLD thermostability.
• The K1E346DPLD mutant demonstrated significantly enhanced thermostability, comparable to the highly stable TH-2PLD.

Conclusions:

• Specific amino acid residues play a critical role in modulating PLD thermostability.
• The Glu346Asp substitution is a key determinant for enhancing PLD thermostability.
• This study provides insights into protein engineering strategies for improving enzyme stability.