Natural ethanol availability directed the evolution of short‐chain alcohol dehydrogenase in animals

Abstract

The presence of alcohol dehydrogenase (ADH) in animals has been assumed to be a consequence of chronic exposure to ethanol. Therefore, in this work we investigate if natural ethanol availability directed the evolution of type II or short‐chain ADHs evolution. In animals, 15‐hydroxyProstaglandin dehydrogenase (PGDH) is the closest homologous to type II ADHs. In contrast, bona fide type II ADHs and ADH‐like proteins appear to be restricted to Diptera (flies). Thus, it can be assumed that the origin of PGDH predates the origin of type II ADHs in Diptera. Adh locus in Drosophila has undergone at least five duplication events, and all them occurred within the Diptera. Because point mutations in Adh can abolish ADH activity in this fly, it can be considered the unique fly enzyme involved in ethanol metabolism.The natural breeding substrates of Drosophila are fermenting fruits. The Drosophila genus is among the most diverse of the Diptera, encompassing >2,000 species. The efficient exploitation of such niches is the reasons for their successful worldwide spreading. Thus, induction of type II Adh by ethanol exposure, a positive correlation between ADH activity and ethanol resistance, ethanol utilization as a nutrient, and the fact that flies and type II Adh diversification occurred in concert with angiosperm diversification, strongly suggest that type II ADHs were recruited to allow larval flies to exploit new restricted niches with high ethanol content. Supported by DGAPA‐UNAM grant IN208510.