title: Evolution of nacre: biochemistry and proteomics of the shell organic matrix of the cephalopod Nautilus macromphalus.
abstract: In mollusks, one of the most widely studied shell textures is nacre, the lustrous aragonitic layer that constitutes the internal components of the shells of several bivalves, a few gastropods,and one cephalopod: the nautilus. Nacre contains a minor organic fraction, which displays a wide range of functions in relation to the biomineralization process. Here, we have biochemically characterized the nacre matrix of the cephalopod Nautilus macromphalus. The acid-soluble matrix contains a mixture of polydisperse and discrete proteins and glycoproteins, which interact with the formation of calcite crystals. In addition, a few bind calcium ions. Furthermore, we have used a proteomic approach,which was applied to the acetic acid-soluble and -insoluble shell matrices, as well as to spots obtained after 2D gel electrophoresis. Our data demonstrate that the insoluble and soluble matrices, although different in their bulk monosaccharide and amino acid compositions, contain numerous shared peptides. Strikingly, most of the obtained partial sequences are entirely new. A few only partly match with bivalvian nacre proteins.Our findings have implications for knowledge of the long-term evolution of molluskan nacre matrices.
authors.affiliation: UMR CNRS 5561 Biogéosciences, Université de Bourgogne, 6 Bd Gabriel, 21000 Dijon, France. benjamin.marie@u-bourgogne.fr
authors.forename: Benjamin
authors.initials: B
authors.lastname: Marie
authors.forename: Frédéric
authors.initials: F
authors.lastname: Marin
authors.forename: Arul
authors.initials: A
authors.lastname: Marie
authors.forename: Laurent
authors.initials: L
authors.lastname: Bédouet
authors.forename: Lionel
authors.initials: L
authors.lastname: Dubost
authors.forename: Gérard
authors.initials: G
authors.lastname: Alcaraz
authors.forename: Christian
authors.initials: C
authors.lastname: Milet
authors.forename: Gilles
authors.initials: G
authors.lastname: Luquet
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D005075:Biological Evolution; D002119:Calcium Carbonate / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D049850:Nautilus / Q000737:chemistry*; D011506:Proteins / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification; D020543:Proteome / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification; D040901:Proteomics / Q000379:methods*; D016415:Sequence Alignment; D012995:Solubility; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D011506:Proteins; D020543:Proteome; D002119:Calcium Carbonate