Chitin Synthesis and Degradation in Crustaceans: A Genomic View and Application

Abstract

Chitin is among the most important components of the crustacean cuticular exoskeleton and intestinal peritrophic matrix. With the progress of genomics and sequencing technology, a large number of gene sequences related to chitin metabolism have been deposited in the GenBank database in recent years. Here, we summarized the genes and pathways associated with the biosynthesis and degradation of chitins in crustaceans based on genomic analyses. We found that chitin biosynthesis genes typically occur in single or two copies, whereas chitin degradation genes are all multiple copies. Moreover, the chitinase genes are significantly expanded in most crustacean genomes. The gene structure and expression pattern of these genes are similar to those of insects, albeit with some specific characteristics. Additionally, the potential applications of the chitin metabolism genes in molting regulation and immune defense, as well as industrial chitin degradation and production, are also summarized in this review.

Genomic and transcriptomic analyses of chitin metabolism enzymes in Tenebrio molitor

“…Amino acid sequence alignment showed that two CHS signature motifs with the respective consensus sequences of EDR and QRRRW in the central catalytic domains are conserved in TmCHS1 and TmCHS2 (Merzendorfer & Zimoch, 2003) (Supporting Information: Figure S2). Another motif "WGTRE" with two conserved amino acids (T and W) that play a catalytic role, thought to be closely related to enzyme activity, is also present in both of them (Merzendorfer & Zimoch, 2003;Zhang et al, 2021). Phylogenetic analysis based on amino acid sequences showed that two members of the CHSs from different insect orders were distinctly grouped into different phylogenic branches, indicating the origin of both CHS1 and CHS2 genes from one ancestral gene (Figure 2).…”

“…Most insect HEXs belong to the GH20 family, which can be divided into six subfamilies: NAG1, NAG2, FDL (fused lobe gene), Hex (hexosaminidase), HexD‐like, and O‐linked N‐acetylglucosaminidase (O‐GlcNAcase) (Xi, Pan, Zhang et al, 2015). Similar to CHSs and CDAs, CHTs and HEXs show distinct expression among tissue sites and developmental stages, indicating biological activities in various physiological functions (Tetreau et al, 2015; Xi, Pan, Zhang et al, 2015; Zhang et al, 2021).…”

Biomass-derived fiber materials for biomedical applications

“…Hence, chitin exhibits a high degree of thermodynamic stability. The poor solubility of chitin in solvent extraction makes the extraction process difficult and laborious (Zhang et al, 2021). With advances in technology and a better understanding of its physiological and biological properties, chitin can be deacetylated and converted into chitosan (CS), a watersoluble polysaccharide (El Knidri et al, 2018).…”

Chitinase (CHI) of Spodoptera frugiperda affects molting development by regulating the metabolism of chitin and trehalose

“…Its main functions include: first, it plays an important role in the growth and development of insects, especially in the process of periodic molting ( Arakane and Muthukrishanan, 2010 ); Second, as the main component of the body surface or trachea epidermis, it protects the internal organs of insects and prevents the invasion of foreign toxins and pathogens to organisms ( Hegedus et al, 2009 ; Doucet and Retnakaran, 2012 ). Based on the important role of chitin in insect growth and development, and the absence of chitin in higher animals, the control of chitin synthesis and degradation has become a safe target for the development of new pesticides ( Oyeleye and Normi, 2018 ; Zhang X. et al, 2021 ; Zhang J. Y. et al, 2021 ; Wang et al, 2022 ). In addition, the purified chitinase has certain insecticidal activity ( Suganthi et al, 2017 ), which has attracted more and more attention.…”

“…If chitinase is continuously expressed and acts, the synthesis of chitin may still be affected after the formation of new epidermis, thus causing the development of insects to be blocked and even death ( Xi et al, 2015 ; Liu et al, 2017 ). Many studies have found that once the expression of chitinase gene was inhibited, the development of insect larvae such as molting, pupation, adult eclosion and wings would be affected ( Zhu et al, 2008b ; Pesch et al, 2016 ; Dong et al, 2020 ; Zhang X. et al, 2021 ).…”