A Recombinant Fungal Chitin Deacetylase Produces Fully Defined Chitosan Oligomers with Novel Patterns of Acetylation

Abstract

We successfully achieved heterologous expression of a fungal chitin deacetylase gene from the basidiomycete Puccinia graminis f. sp. tritici in the periplasm of E. coli as a fusion protein with the maltose-binding protein; this strategy allows the production of these difficult-to-express enzymes in sufficient quantities for them to be characterized and optimized through protein engineering. Here, the recombinant enzyme was used to produce partially acetylated chitosan oligosaccharides from chitin oligomers, whereby the pronounced regioselectivity of the enzyme led to the production of defined products with novel patterns of acetylation. This approach widens the scope for both the production and functional analysis of chitosan oligomers and thus will eventually allow the detailed molecular structure-function relationships of biologically active chitosans to be studied, which is essential for developing applications for these functional biopolymers for a circular bioeconomy, e.g., in agriculture, medicine, cosmetics, and food sciences.