Enhancing antifungal activity of chitinase by fusion of chitin binding domain at both termini

Abstract:

[Objective] To develop a simple method to improve the enzymatic and antifungal activity of chitinase by fusion of chitin binding domain at both termini. [Methods] The chimeric and truncated chitinases were constructed using the unique glycoside hydrolase family 19 chitinase in Streptomyces alfalae ACCC40021 as template, and expressed in Escherichia coli. The 3,5-dinitrosalicylic acid (DNS) method was used to determine the enzyme activity with colloid chitin as the substrate. [Results] CatD_ChiB (catalytic domain), rChiB (N-terminal chitin-binding domain) and DChBD_ChiB (double chitin-binding domain) were successfully constructed and expressed in E. coli BL21(DE3). Compared to CatD_ChiB and rChiB, DChBD_ChiB improved the binding ability and activity towards colloidal chitin, α-chitin and chitin from Aspergillus niger. Furthermore, antifungal activity was enhanced against plant pathogenic fungus Trichoderma longibranchiatum. [Conclusion] A simple, feasible and efficient method was developed to improve the enzymatic and antifungal activity of chitinase by fusion of chitin binding domain on both C-and N-terminus of protein.