Chitinases of filamentous fungi: a large group of diverse proteins with multiple physiological functions

Chitin is the second most abundant natural biopolymer and the main structural component of invertebrate exoskeletons and cell walls of filamentous fungi. Fungal chitinases have multiple physiological functions including the degradation of exogenous chitin and cell wall remodelling during hyphal growth, but the regulation of the chitinolytic systems of filamentous fungi is not well understood. Fungi have on average between 10 and 25 different chitinases, but only the increasing number of fungal genome sequencing projects in the last few years has enabled us to assess the whole range and diversity of fungal chitinases. In this review the variety, domain architecture and subgroups of chitinases of filamentous fungi are shown, and how these data integrate with that from molecular biological studies on chitinases are discussed.