Novel insights into conserved biomineralization mechanisms revealed from a cold-water scleractinian coral skeletal proteome
Stony corals exhibit striking morphological plasticity across diverse environments and trophic strategies, raising fundamental questions about the conservation of their biomineralization machinery. Here, we characterize the skeletal organic matrix proteome of the cold-water, asymbiotic coral Desmophyllum pertusum and compare it with skeletal proteomes from a facultatively photosymbiotic temperate coral and an obligately photosymbiotic subtropical coral. Despite pronounced differences in habitat, symbiotic status, and skeletal micro-density, we observe convergence on a conserved "biomineralization toolkit". Comparative proteomics, genomics, and structural predictions reveal that this toolkit integrates diverse acidic matrix proteins, carbonic anhydrases, adhesion and structural proteins, and signaling components with multiple cellular export pathways. Together, these findings redefine coral biomineralization as a dynamic, coordinated network of cellular pathways rather than a static assemblage of matrix components. The symbiont-free model D. pertusum provides a mechanistic framework for dissecting coral calcification across environments and for assessing the resilience of this conserved machinery.