Project description:Coral skeletons are materials composed of inorganic aragonitic fibers, proteins, sugars and lipids that are highly organized to form a solid body upon which the animals live. The skeleton contains more than 30 proteins, all of which are encoded in the animal genome and secreted during the biomineralization process. How these proteins are spatially related is unknown. Using a combination of chemical crosslinking and high-resolution tandem mass spectrometry, we identify, for the first time. the spatial interactions of the skeletal proteins within a stony coral. Our subsequent network analysis revealed several coral acid-rich proteins (CARPs) are invariably associated with carbonic anhydrase(s), alpha-collagen, cadherins and other calcium binding proteins. These interactions clearly show that protein-protein interactions in coral skeletons are highly coordinated and are key to understanding the formation and persistence of coral skeletons through time
Project description:Black corals, ecologically important cnidarians found from shallow to deep ocean depths, form a strong yet flexible skeleton of sclerotized chitin and other biomolecules including proteins. The structure and mechanical properties of the chitin component of the skeleton have been well-characterized. However, the protein component has remained a mystery. Here we used liquid chromatography-tandem mass spectrometry to sequence proteins extracted from two species of common Red Sea black corals following either one or two cleaning steps. We detected hundreds of proteins between the two corals, nearly 70 of which are each others’ reciprocal best BLAST hit. Unlike stony corals, only a few of the detected proteins were moderately acidic (biased toward aspartic and/or glutamic acid residues) suggesting less of a role for these types of proteins in black coral skeleton formation as compared to stony corals. No distinct chitin binding domains were found in the proteins, but proteins annotated as having a role in protein and chitin modifications were detected. Our results support the integral role of proteins in black coral skeleton formation, structure, and function.