Structure, regulation, and potential applications of insect chitin- metabolizing enzymes

Abstract

Chitin is a vital component of insect exoskeleton and peritrophic matrix and because of this reason a potential target for insecticidal agents. Chitin-metabolizing enzymes, viz., chitin synthases and chitinases, belong to the glycoside hydrolase superfamily (GH18). Chitin synthases are involved in deposition of new cuticle during molting and also ideal for development of insecticidal agents. Chitinases are considered as an essential enzyme for insect growth and development being involved in molting and various other physiological processes, i.e., cuticle turnover, regulation of abdominal contraction and wing expansion, digestion, immunity, and natural defense. Chitinases possess multi-domain architecture, i.e., chitin-binding domain, Ser-/Thr-rich linker domains, catalytic domains, fibronectin, and mucin-like domains. Knockdown of both the enzymes resulted into irregularities in metamorphosis. Diverse group of chitinase-like proteins have also been detected in insect species that possess chitin-binding domains but do not exhibit catalytic activity. Development of chitinases as defensive agents against chitin-bearing insect pests and pathogens will generate new knowledge and innovative processes for biocontrol advancements.