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Lineage-Specific Duplication and Loss of Pepsinogen Genes in Hominoid Evolution

Narita, Yuichi ; Oda, Sen-ichi ; Takenaka, Osamu ; Kageyama, Takashi

In: Journal of Molecular Evolution, 2010, vol. 70, no. 4, p. 313-324

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    Titre
    • Lineage-Specific Duplication and Loss of Pepsinogen Genes in Hominoid Evolution
    Auteur
    • Narita, Yuichi. Center for Human Evolution Modeling Research, Primate Research Institute, Kyoto University, 484-8506, Inuyama, Japan
    • Oda, Sen-ichi. Laboratory of Animal Management, Nagoya University School of Bio-Agricultural Sciences, 464-0852, Nagoya, Japan
    • Takenaka, Osamu. Department of Cellular and Molecular Biology, Primate Research Institute, Kyoto University, 484-8506, Inuyama, Japan
    • Kageyama, Takashi. Center for Human Evolution Modeling Research, Primate Research Institute, Kyoto University, 484-8506, Inuyama, Japan
    Type de document
    • Postprint
    Langue
    • Anglais
    Publié dans
    • Journal of Molecular Evolution, 2010, vol. 70, no. 4, p. 313-324. Springer-Verlag
    Autre version électronique
    Identifiant OAI-PMH
    • oai:doc.rero.ch:322410
    Summary
    Fourteen different pepsinogen-A cDNAs and one pepsinogen-C cDNA have been cloned from gastric mucosa of the orangutan, Pongo pygmaeus. Encoded pepsinogens A were classified into two groups, i.e., types A1 and A2, which are different in acidic character. The occurrence of 9 and 5 alleles of A1 and A2 genes (at least 5 and 3 loci), respectively was anticipated. Respective orthologous genes are present in the chimpanzee genome although their copy numbers are much smaller than those of the orangutan genes. Only A1 genes are present in the human probably due to the loss of the A2 gene. Molecular phylogenetic analyses showed that A1 and A2 genes diverged before the speciation of great hominoids. Further reduplications of respective genes occurred several times in the orangutan lineage, with much higher frequencies than those occurred in the chimpanzee and human lineages. The rates of non-synonymous substitutions were higher than those of synonymous ones in the lineage of A2 genes, implying the contribution of the positive selection on the encoded enzymes. Several sites of pepsin moieties were indeed found to be under positive selection, and most of them locate on the surface of the molecule, being involved in the conformational flexibility. Deduced from the known genomic structures of pepsinogen-A genes of primates and other mammals, the duplication/loss were frequent during their evolution. The extreme multiplication in the orangutan might be advantageous for digestion of herbaceous foods due to the increase in the level of enzymes in stomach and the diversification of enzyme specificity