Nacre, the iridescent material found in pearls and shells of molluscs, is formed through an extraordinary process of matrix-assisted biomineralization. Despite recent advances, many parts of the biomineralization process and its evolutionary origin remain a mystery. The pearl oyster Pinctada fucata martensii is a well-known master of biomineralization, but the molecular mechanisms underlie its production of remarkable shells and pearls is not fully understood. We sequenced the highly polymorphic genome of the pearl oyster and conducted multi-omic and biochemical studies to probe nacre formation. We identified a large set of novel proteins participating in matrix-framework formation, many in expanded families, including components similar to that found in vertebrate bones such as collagen-related VWA-containing proteins (VWAP), fibronectin, chondroitin sulfotransferases and regulatory elements. Considering that there are only collagen-based matrices in vertebrate bones and chitin-based matrices in most invertebrate skeletons, the presence of both chitin and elements of collagen-based matrices in nacre matrices suggests that elements of chitin- and collagen-based matrices are deeply rooted and might be part of an ancient biomineralizing matrix. Our results expand the current shell matrix-framework model and provide new insights into the evolution of diverse biomineralization systems.

Read the peer-reviewed publication(s):

(PubMed: 28873964)

Accessions (data generated as part of this study):

BioProject: PRJNA283019
PRIDE: PXD006786