In-silico analysis of associated chitinolytic enzyme structures from aquatic bacteria

Abstract

Chitin is a naturally occurring polymer composed of two monomeric units and exists in three forms, namely α-, β-, and γ-chitin, which differ in their structural arrangement. Chitinolytic enzymes, known as chitinases, degrade chitin into low-molecular-weight products called chitooligomers. Extremophilic chitinases have attracted considerable interest due to their ability to function under extreme environmental conditions, making them advantageous for various industrial and biotechnological applications. In this study, an in-silico analysis was performed to identify putative extremophilic candidates of GH18 chitinases at various aquatic environmental adaptations, including halophilic, thermophilic, psychrophilic, and piezophilic characteristics, were considered during BLASTp screening. Five putative candidates were selected for further analysis: Colwellia sp. D2M02 (WP_215980056.1), Thalassomonas viridans (WP_084724197.1), Bacillus thuringiensis (WP_09832960.1), Brevibacillus formosus (WP_21966082.1), and Bacillus toyonensis (WP_098644165.1). To investigate the relationships among these candidates, analyses including primary structure characterization, multiple sequence alignment and protein domain prediction, and phylogenetic tree construction were performed. Physicochemical analyses provided insights into their chemical properties. Secondary structure prediction was carried out using RaptorX, while tertiary structure models were generated using SWISS-MODEL, RaptorX, and I-TASSER. The generated 3D models were subsequently validated using PROCHECK and Verify3D to determine the most reliable structural models. Overall, the selected putative candidates are expected to be promising for industrial-scale chitinase production due to their ability to withstand multiple extreme environmental conditions, indicating their potential as polyextremophilic enzymes.