Expression and biochemical characterization of a novel chitinase ChiT-7 from the metagenome in the soil of a mangrove tidal flat in China

• Published in: International journal of biological macromolecules Vol. 158; pp. 1125 - 1134
• Main Authors: Li, Ren Kuan, Hu, Ya Juan, Ng, Tzi Bun, Guo, Bing Qi, Zhou, Zi He, Zhao, Jing, Ye, Xiu Yun
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.09.2020
• Subjects: Characterization; Chitinase; Mangrove tidal flat; Chitinase; Characterization; Mangrove tidal flat
• ISSN: 0141-8130; 1879-0003
• DOI: 10.1016/j.ijbiomac.2020.04.242

Chitinases play an important role in the process of chitin bioavailability. In this study, we cloned a new chitinase gene and characterized its recombinant protein. The new 1251 bp gene of chitinase (ChiT-7) was cloned from the metagenome of the mangrove tidal flat soil in the city of Zhangzhou in Fujian Province (China) by genome walking. The gene encoded a mature protein with 381 amino acids, which manifested certain sequence similarity (59% identity) to characterized GH18 chitinases. The mature protein of ChiT-7 was successfully expressed in E. coli BL21 (DE3). After purification, the specific activity of the recombinant enzyme was 0.63 U/mg at the optimal pH of 6.0 and the optimal temperature of 45 °C. The rChiT-7 was active over a wide pH range, and the residual enzyme activity reached 80% or higher at 30 °C–50 °C. rChiT-7 hydrolyzed colloidal chitin with (GlcNAc)2 and GlcNAc as the main final products. Structural analysis of ChiT-7 indicated that ChiT-7 could be a processive chitinase. rChiT-7 manifested characteristics analogous to those of fungi and actinomycetes and exhibited sequence homology.