Duplicated Gene Evolution of the Primate Alcohol Dehydrogenase Family

AbstractThe mammalian alcohol dehydrogenase (ADH: EC1.1.1.1) enzymes metabolize a wide range of alcohol and carbonyl compounds. The ADH enzyme family is classified into five classes (I–V) based on biochemical properties and nucleotide/amino acid sequence similarity. Each class of ADH shares 60–70% sequence similarity with other classes of ADH in the same species, and ADHs within the same class in the same species share more than 80% sequence similarity. The high similarity among ADHs suggests that their genes have evolved by multiple duplications. Previous studies based on Southern hybridization data have identified copy number variation of Class I ADH genes in mammals: the mouse has only one Class I gene, some other mammals have two genes, whereas all primates examined have at least three Class I genes. Our previous study showed that great apes (human, chimpanzee, bonobo, gorilla, orangutan) and Old World monkeys (baboon) have three or more Class I genes that have evolved independently, escaping from homogenization by gene conversion. In this review, we revisit the puzzle of the copy number variation in the primate ADH gene family by searching the literature and genome databases and propose a hypothesis that the primate frugivorous behavior has maintained the duplicated genes because of the necessity of digesting ethanol generated by fermentation of fruit sugar.KeywordsGene ConversionWhole Genome SequencingBefore PresentWhole Genome Sequencing DataMammalian RadiationThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.