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
- 230 Downloads
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.
KeywordsEnamelin Evolution Teeth Mammals Purifying selection Positive selection
We thank Mehboob Chilwan (Erasmus, University of Keele, UK) for English corrections. This work was supported by CNRS and UPMC (UMR 7138) Grants.
- Dayhoff MO, Schwartz R, Orcutt BC (1978) A model of evolutionary change in proteins, matrixes for detecting distant relationships. In: Dayhoff MO (ed) Atlas of protein sequence and structure, vol 5. National Biomedical Research Foundation, Washington, DC, pp 345–358Google Scholar
- Fukae M, Tanabe T (1985) Separation of non-amelogenin component from purified amelogenin preparation of immature porcine enamel. Jpn J Oral Biol 27:1249–1251Google Scholar
- Masuya H, Shimizu K, Sezutsu H, Sakuraba Y, Nagano J, Shimizu A, Fujimoto N, Kawai A, Miura I, Kaneda H, Kobayashi K, Ishijima J, Maeda T, Gondo Y, Noda T, Wakana S, Shiroishi T (2005) Enamelin (Enam) is essential for amelogenesis: ENU-induced mouse mutants as models for different clinical subtypes of human amelogenesis imperfecta (AI). Hum Mol Genet 14:575–583CrossRefPubMedGoogle Scholar
- Uchida T, Tanabe T, Fukae M, Shimizu M, Yamada M, Miake K, Kobayashi S (1991a) Immunochemical and immunohistochemical studies, using antisera against porcine 25 kDa amelogenin, 89 kDa enamelin and the 13–17 kDa nonamelogenins, on immature enamel of the pig and rat. Histochemistry 96:129–138CrossRefPubMedGoogle Scholar
- Warren WC, Hillier LW, Marshall Graves JA, Birney E, Ponting CP, Grutzner F, Belov K, Miller W, Clarke L, Chinwalla AT, Yang SP, Heger A, Locke DP, Miethke P, Waters PD, Veyrunes F, Fulton L, Fulton B, Graves T, Wallis J, Puente XS, Lopez-Otin C, Ordonez GR, Eichler EE, Chen L, Cheng Z, Deakin JE, Alsop A, Thompson K, Kirby P, Papenfuss AT, Wakefield MJ, Olender T, Lancet D, Huttley GA, Smit AF, Pask A, Temple-Smith P, Batzer MA, Walker JA, Konkel MK, Harris RS, Whittington CM, Wong ES, Gemmell NJ, Buschiazzo E, Vargas Jentzsch IM, Merkel A, Schmitz J, Zemann A, Churakov G, Kriegs JO, Brosius J, Murchison EP, Sachidanandam R, Smith C, Hannon GJ, Tsend-Ayush E, McMillan D, Attenborough R, Rens W, Ferguson-Smith M, Lefevre CM, Sharp JA, Nicholas KR, Ray DA, Kube M, Reinhardt R, Pringle TH, Taylor J, Jones RC, Nixon B, Dacheux JL, Niwa H, Sekita Y, Huang X, Stark A, Kheradpour P, Kellis M, Flicek P, Chen Y, Webber C, Hardison R, Nelson J, Hallsworth-Pepin K, Delehaunty K, Markovic C, Minx P, Feng Y, Kremitzki C, Mitreva M, Glasscock J, Wylie T, Wohldmann P, Thiru P, Nhan MN, Pohl CS, Smith SM, Hou S, Renfree MB (2008) Genome analysis of the platypus reveals unique signatures of evolution. Nature 453:175–183CrossRefPubMedGoogle Scholar