Cloning and Expression of a New Chitinase from Carnivorous Plants Drosera capensis

Abstract

A novel chi19 gene encoding the chitinase, belonging to the glycosyl hydrolase family 19 from the predatory plant Drosera capensis is cloned and expressed in the E. coli bacterial system. The amino acid sequence of the translated enzyme consists of 325 a.a. divided into four functional parts: the N-terminal signal sequence and of the catalytic and chitin-binding domains that were linked by the –S–P- linker. The chi19 gene is expressed in two forms: with and without a chitin-binding domain. Refolding is carried out and homogeneous soluble forms are obtained for both variants of the enzyme. The chitinases obtained exhibit predominantly specific activity towards crystalline chitin, with the optimal pH level ranging from 5.0 to 5.5 and the optimum temperature in the range of 52 to 55°C for both forms of the enzyme. The catalytic activity of the full-sized form of chitinase was 360 U/g with a 64% decrease of the catalytic activity for the form with the chitin-binding domain removed.