An overview of viral chitinases: General properties and biotechnological potential

Chitin is a biopolymer profusely present in nature and of pivotal importance as a structural component in cells. It is degraded by chitinases, enzymes naturally produced by different organisms. Chitinases are proteins enrolled in many cellular mechanisms, including the remodeling process of the fungal cell wall, the cell growth process, the autolysis of filamentous fungi, and cell separation of yeasts, among others. These enzymes also have properties with different biotechnological applications. They are used to produce polymers, for biological control, biofilm formation, and as antitumor and anti-inflammatory target molecules. Chitinases are classified into different glycoside hydrolase (GH) families and are widespread in microorganisms, including viruses. Among them, the GH18 family is highly predominant in the viral genomes, being present and active enzymes in baculoviruses and nucleocytoplasmic large DNA viruses (NCLDV), especially chloroviruses from the Phycodnaviridae family. These viral enzymes contain one or more GH domains and seem to be involved during the viral replication cycle. Curiously, only a few DNA viruses have these enzymes, and studying their properties could be a key feature for biological and biotechnological novelties. Here, we provide an overview of viral chitinases and their probable function in viral infection, showing evidence of at least two distinct origins for these enzymes. Finally, we discuss how these enzymes can be applied as biotechnological tools and what one can expect for the coming years on these GHs.