title: Evolutionary analysis of mammalian enamelin, the largest enamel protein, supports a crucial role for the 32-kDa peptide and reveals selective adaptation in rodents and primates.
abstract: Enamelin (ENAM) plays an important role in the mineralization of the forming enamel matrix. We have performed an evolutionary analysis of mammalian ENAM to identify highly conserved residues or regions that could have important function (selective pressure), to predict mutations that could be associated with amelogenesis imperfecta in humans, and to identify possible adaptive evolution of ENAM during 200 million years ago of mammalian evolution. In order to fulfil these objectives, we obtained 36-ENAM sequences that are representative of the mammalian lineages. Our results show a remarkably high conservation pattern in the region of the 32-kDa fragment of ENAM, especially its phosphorylation, glycosylation, and proteolytic sites. In primates and rodents we also identified several sites under positive selection, which could indicate recent evolutionary changes in ENAM function. Furthermore, the analysis of the unusual signal peptide provided new insights on the possible regulation of ENAM secretion, a hypothesis that should be tested in the near future. Taken together, these findings improve our understanding of ENAM evolution and provide new information that would be useful for further investigation of ENAM function as well as for the validation of mutations leading to amelogenesis imperfecta.
authors.affiliation: Université Pierre et Marie Curie, UMR 7138-Systématique, Adaptation, Evolution, Case 5, 7 Quai Saint-Bernard, Bâtiment A, 4e étage, 75005, Paris, France.
authors.forename: Nawfal
authors.initials: N
authors.lastname: Al-Hashimi
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Sire
authors.forename: Sidney
authors.initials: S
authors.lastname: Delgado
mesh_terms: D000567:Amelogenesis Imperfecta / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D003743:Dental Enamel / Q000378:metabolism; D003746:Dental Enamel Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D019143:Evolution, Molecular; D005786:Gene Expression Regulation; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D010455:Peptides / Q000235:genetics / Q000378:metabolism; D011323:Primates / Q000235:genetics*; D021382:Protein Sorting Signals; D012377:Rodentia / Q000235:genetics*; D012641:Selection, Genetic; D014070:Tooth / Q000378:metabolism
chemical_list: D003746:Dental Enamel Proteins; D010455:Peptides; D021382:Protein Sorting Signals; C038456:tuftelin