Characteristics and mechanism of a novel chitinase mutant from Trichoderma harzianum with enhanced activity

Abstract Background: Chitinase from Trichoderma harzianum could inhibit various chitin-containing pathogens. In this study, a mutant of Chit42 (Chit42m) with high enzyme activity was established by error-prone PCR method. Results: The Chit42m with three amino acids substitutions (D100G/I166V/A382P) was obtained from 1230 colonies. The activity of the Chit42m was enhanced by 1.26 times and affinity increased by 3.2 folds. The Chit42m showed the optimum temperature was 50 °C and pH 7.5. Conclusion: Structural model and molecular docking analysis suggested that A382P may affect the catalytic activity of enzymes by affecting the conformation of key residues D169 and E171 related to catalysis, while I166V probably affects the affinity of chitin and enzymes by influencing the conformation of important substrate binding residues R52 and Y293. D100G had little effect on the changes of enzyme activity. This would put insight into the study of the site-specific mutations and provide promising gene material for the directed evolution chitinase.