title: Proteomics analysis of the nacre soluble and insoluble proteins from the oyster Pinctada margaritifera.
abstract: Shell nacre is laid upon an organic cell-free matrix, part of which, paradoxically, is water soluble and displays biological activities. Proteins in the native shell also constitute an insoluble network and offer a model for studying supramolecular organization as a means of self-ordering. Consequently, difficulties are encountered in extraction and purification strategies for protein characterization. In this work, water-soluble proteins and the insoluble conhiolin residue of the nacre of Pinctada margaritifera matrix were analyzed via a proteomics approach. Two sequences homologous to nacre matrix proteins of other Pinctada species were identified in the water-soluble extract. One of them is known as a fundamental component of the insoluble organic matrix of nacre. In the conchiolin, the insoluble residue, four homologs of Pinctada nacre matrix proteins were found. Two of them were the same as the molecules characterized in the water-soluble extract. Results established that soluble and insoluble proteins of the nacre organic matrix share constitutive material. Surprisingly, a peptide in the conchiolin residue was found homologous to a prismatic matrix protein of Pinctada fucata, suggesting that prismatic and nacre matrices may share common proteins. The insoluble properties of shell matrix proteins appear to arise from structural organization via multimerization. The oxidative activity, found in the water-soluble fraction of the nacre matrix, is proposed as a leading process in the transformation of transient soluble proteins into the insoluble network of conchiolin during nacre growth.
authors.affiliation: Département des Milieux et Peuplements Aquatiques, UMR 5178, CNRS-MNHN Biologie des Organismes Marins et Ecosystèmes, ERT Valorisation de Molécules Bioactives d'Origine Marine, Muséum National d'Histoire Naturelle, Paris, France. bedouet@mnhn.fr
authors.forename: Laurent
authors.initials: L
authors.lastname: Bédouet
authors.forename: Arul
authors.initials: A
authors.lastname: Marie
authors.forename: Lionel
authors.initials: L
authors.lastname: Dubost
authors.forename: Jean
authors.initials: J
authors.lastname: Péduzzi
authors.forename: Denis
authors.initials: D
authors.lastname: Duplat
authors.forename: Sophie
authors.initials: S
authors.lastname: Berland
authors.forename: Marion
authors.initials: M
authors.lastname: Puisségur
authors.forename: Hélène
authors.initials: H
authors.lastname: Boulzaguet
authors.forename: Marthe
authors.initials: M
authors.lastname: Rousseau
authors.forename: Christian
authors.initials: C
authors.lastname: Milet
authors.forename: Evelyne
authors.initials: E
authors.lastname: Lopez
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002853:Chromatography, Liquid / Q000662:veterinary; D006863:Hydrogen-Ion Concentration; D013058:Mass Spectrometry / Q000662:veterinary; D008969:Molecular Sequence Data; D049911:Pinctada / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D011506:Proteins / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification; D020543:Proteome / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification; D040901:Proteomics / Q000379:methods*; D012995:Solubility; D014867:Water / Q000737:chemistry
chemical_list: D000596:Amino Acids; D011506:Proteins; D020543:Proteome; D014867:Water; C010699:conchiolin