The importance of subclasses of chitin synthase enzymes with myosin-like domains for the fitness of fungi

Chitin represents one of the most important components of the fungal cell wall. The multiplicity of chitin synthase (Chs) enzymes found in filamentous fungi underlines the importance of chitin in these organisms. Among this group of fungal enzymes, two classes, V and VII, are armed with myosin motors, constituting the MMD-Chs (Myosin Motor Domain - Chitin synthases) that are found in filamentous fungi and are absent in most yeast species. These enzymes play a critical role in promoting the synthesis of chitin at the hyphal tip, thus influencing fungal growth and the architecture of fungal infection structures. Other processes in which these enzymes are important are in osmo- and H2O2-tolerance, the ability to grow at 37 °C and in conidiogenesis. This review is focussed on the classification, structure and function of these enzymes describing the fundamental role of these enzymes in the ability of filamentous fungi to infect plants and their possible involvement in infections of animals. Moreover, data obtained with deletant mutants of this family of proteins indicates that they have potential as targets for novel antifungals.