Cloning, expression, and characterization of a GH 19-type chitinase with antifungal activity from Lysobacter sp. MK9-1

The chitin-assimilating gram-negative bacterium, Lysobacter sp. MK9-1, was isolated from soil and was the source of a glycoside hydrolase family 19-type chitinase (Chi19MK) gene that is 933-bp long and encodes a 311-residue protein. The deduced amino acid sequence of Chi19MK includes a signal peptide, an uncharacterized sequence, a carbohydrate-binding module family 12-type chitin binding domain, and a catalytic domain. The catalytic domain of Chi19MK is approximately 60% similar to those of ChiB from Burkholderia gladioli CHB101, chitinase N (ChiN) from Chitiniphilus shinanonensis SAY3(T), ChiF from Streptomyces coelicolor A3(2), Chi30 from Streptomyces olivaceoviridisis, ChiA from Streptomyces cyaneus SP-27, and ChiC from Streptomyces griseus HUT6037. Chi19MK lacking the signal and uncharacterized sequences (Chi19MK Delta NTerm) was expressed in Escherichia coli Rosetta-gami B(DE3), resulting in significant chitinase activity in the soluble fraction. Purified Chi19MK Delta NTerm hydrolyzed colloidal chitin and released disaccharide. Furthermore, Chi19MK Delta NTerm inhibited hyphal extension in Trichoderma reesei and Schizophyllum commune. Based on quantitative antifungal activity assays, Chi19MK Delta NTerm inhibits the growth of Trichoderma viride with an IC50 value of 0.81 mu M. (C) 2020, The Society for Biotechnology, Japan. All rights reserved.

Automated summary

The chitin-assimilating bacterium Lysobacter sp. MK9-1, isolated from soil, produces the Chi19MK gene which encodes a chitinase enzyme. The purified Chi19MK enzyme shows significant chitinase activity and inhibits fungal growth.