Dr Frédéric Marin - Mollusk shell matrices: unexpected functions in biomineralization

Réalisation : 24 mars 2021 Mise en ligne : 24 mars 2021
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To construct their skeletons, all metazoans secrete a complex array ofmacromolecules that are supposed to display key-functions in biomineralization,such as crystal nucleation and crystal growth orientation. These macromolecules- generally less than 1% of the skeletal weight - are occluded during skeletalgrowth and can be retrieved and analyzed by dissolving the mineral phase. Theycomprise proteins, glycoproteins, peptides, polysaccharides, and sometimes,lipids, pigments and metabolites. They constitute collectively the 'calcifyingmatrix', from which proteins and glycoproteins are the most studied.

 In the last decade, the coupling of high-throughput screening techniques(transcriptomics + proteomics) has allowed the identification of a large numberof proteins of the "skeletal repertoires", in diverse metazoan phyla.To give an idea, in mollusks, more than 1000 proteins are now listed as putativeshell proteins, in about 30 different genera.

Proteomic data underline the diversity of these proteins, which goesalong with the diversity of functions required for calcifying a skeleton. Besideexpected members (acidic proteins, proteins with hydrophobic domains), shellproteomes (aka 'shellomes') reveal a large variety of proteins with verydifferent low complexity domains. Above all, the surprise comes from thediscovery of a huge set of proteins involved in immunity and defense mechanismsin general. This last aspect will be particularly discussed in my talk.


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