The search for proteins involved in the formation of crustacean cuticular structures

Crustacean cuticular structures are key features formed during a molt cycle. These structures are complex biomaterials comprising chitin and different mineral forms in distinct scaffold organizations. The formation of these complex biomaterials is controlled by the organic extracellular matrix including structural proteins. Since cuticular structures are formed de novo during each molt cycle, the spatial and temporal expression patterns of structural proteins are tightly linked to molt cycle events. As a model scenario, we demonstrate the molt-related pattern of expression of the gene encoding GAP65, a core structural protein involved in the formation of the cuticular structures of Cherax quadricarinatus. Based on this typical pattern of expression and using a binary-patterning approach, which is a specialized tool for the study of molt-related proteins, we revealed and characterized additional candidate proteins involved in the formation of crustacean cuticular structures. We propose that our approach be applied as a framework in the search for proteins involved in the formation of the crustacean cuticle. To stimulate research on this important aspect of structural biology, we put forward a schematic representation of the extracellular matrix and its proteins in three cuticular structures of C. quadricarinatus, the gastroliths, the mandibles, and the mineralized cuticle.