Proteomic analysis of the shell organic matrix of Spondylus Gaederopus

This work reports a comprehensive and integrated microstructural, biochemical and proteomics study on the shell matrix of Spondylus gaederopus, the Mediterranean thorny oyster. We investigate the skeletal matrix proteins which are involved in biomineralization and compare the identified Spondylus sequences with other shell proteins, that are publicly available in databases. Using high-resolution liquid chromatography tandem mass spectrometry (LC-MS/MS) we characterized several shell protein fractions, isolated by different bleaching treatments. We identified six shell proteins, which also displayed features and domains typically found in biomineralized tissues, including the prevalence of intrinsically disordered regions. However, many reconstructed peptide sequences (de novo) could not be matched to any known shell proteins and we suggest that these probably represent lineage-specific sequences. The proteomic data implies that Spondylus may have evolved a distinct molecular toolkit for biomineralization. Using high-resolution liquid chromatography tandem mass spectrometry (LC-MS/MS) we characterized several shell protein fractions, isolated by different bleaching treatments. Six shell proteins were identified, which displayed features and domains typically found in biomineralized tissues, including the prevalence of intrinsically disordered regions. However, most of the reconstructed peptide sequences (de novo) could not be matched to any known shell proteins and probably represent lineage-specific sequences.