Biochemical Characterization of a Carrageenase, Car1383, Derived From Associated Bacteria of Antarctic Macroalgae

• Published in: Frontiers in Microbiology
• Main Authors: Jiang Li, Xiaoqian Gu, Qian Zhang, Liping Fu, Jiaojiao Tan, Luying Zhao
• Format: Article in Journal/Newspaper
• Language: English
• Published: Frontiers Media S.A. 2022
• Subjects: carrageenase; Antarctic macroalgae; associated bacteria; metagenome; site-directed mutagenesis; Microbiology; QR1-502; Antarctic; Antarc*
• Online Access: https://doi.org/10.3389/fmicb.2022.851182; https://doaj.org/article/59edea3c3ecd48deb320ebd3af5278ed

A carrageenase gene, car1383, was obtained from the metagenome of Antarctic macroalgae-associated bacteria. The amino acid sequence of its product showed up to 33% similarity with other carrageenases and contained a GH16-family motif. The recombinant Car1383 was heterologously expressed in Eschericia coli and exhibited maximal activity at 50°C and pH 6.0, with a Km of 6.51 mg/ml and a Vmax of 55.77 U/mg. Its activity was enhanced by some cations (Na+, K+, and Fe2+), but inhibited or inactivated by others (Sr2+, Ca2+, Ni2+, Ba2+, Mn2+, Cu2+, Fe3+, and Mg2+). Car1383 degraded carrageenan into neocarrabiose and neocarratetraose. Site-directed mutagenesis indicated that putative active sites, E190 and E195, conserved sites, W183 and G255, play important roles in Car1383 activity. This study provides a new candidate for the industrial preparation of bioactive algal oligosaccharides.