A structural and biochemical model of processive chitin synthesis

Chitin synthases (CHS) produce chitin, an essential component of the fungal cell wall. The molecular mechanism of processive chitin synthesis is not understood, limiting the discovery of new inhibitors of this enzyme class. We have identified the bacterial glycosyltransferase NodC as an appropriate model system to study the general structure and reaction mechanism of CHS. A highthroughput screening compatible novel assay demonstrates that inhibitors of fungal CHS also inhibit NodC. A structural model of NodC, based on the recently published BcsA cellulose synthase structure, enabled probing of the catalytic mechanism by mutagenesis, demonstrating the essential roles of the DD and QxxRW catalytic motifs. NodC membrane topology is mapped, validating the structural model. Together, these approaches give insight into the CHS structure and mechanism and provide a platform for discovery of inhibitors for this antifungal target. ________________________________________