Click here to close Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly. We suggest using a current version of Chrome, FireFox, or Safari.
BMC Genomics March 20, 2014; 15 216.

The Xenopus alcohol dehydrogenase gene family: characterization and comparative analysis incorporating amphibian and reptilian genomes.

Borràs E , Albalat R , Duester G , Parés X , Farrés J .

BACKGROUND: The alcohol dehydrogenase (ADH) gene family uniquely illustrates the concept of enzymogenesis. In vertebrates, tandem duplications gave rise to a multiplicity of forms that have been classified in eight enzyme classes, according to primary structure and function. Some of these classes appear to be exclusive of particular organisms, such as the frog ADH8, a unique NADP+-dependent ADH enzyme. This work describes the ADH system of Xenopus, as a model organism, and explores the first amphibian and reptilian genomes released in order to contribute towards a better knowledge of the vertebrate ADH gene family. RESULTS: Xenopus cDNA and genomic sequences along with expressed sequence tags (ESTs) were used in phylogenetic analyses and structure-function correlations of amphibian ADHs. Novel ADH sequences identified in the genomes of Anolis carolinensis (anole lizard) and Pelodiscus sinensis (turtle) were also included in these studies. Tissue and stage-specific libraries provided expression data, which has been supported by mRNA detection in Xenopus laevis tissues and regulatory elements in promoter regions. Exon-intron boundaries, position and orientation of ADH genes were deduced from the amphibian and reptilian genome assemblies, thus revealing syntenic regions and gene rearrangements with respect to the human genome. Our results reveal the high complexity of the ADH system in amphibians, with eleven genes, coding for seven enzyme classes in Xenopus tropicalis. Frogs possess the amphibian-specific ADH8 and the novel ADH1-derived forms ADH9 and ADH10. In addition, they exhibit ADH1, ADH2, ADH3 and ADH7, also present in reptiles and birds. Class-specific signatures have been assigned to ADH7, and ancestral ADH2 is predicted to be a mixed-class as the ostrich enzyme, structurally close to mammalian ADH2 but with class-I kinetic properties. Remarkably, many ADH1 and ADH7 forms are observed in the lizard, probably due to lineage-specific duplications. ADH4 is not present in amphibians and reptiles. CONCLUSIONS: The study of the ancient forms of ADH2 and ADH7 sheds new light on the evolution of the vertebrate ADH system, whereas the special features showed by the novel forms point to the acquisition of new functions following the ADH gene family expansion which occurred in amphibians.

PubMed ID: 24649825
PMC ID: PMC4028059
Article link: BMC Genomics

Genes referenced: adh1 adh1a adh1b adh1c adh4 adh5 adh7 adhfe1 ank1 anp32b bank1 coro1c coro2a dapp1 ddit4l dnaja2 dnajb14 eif4e h2ac21 h2az1 metap1 ncbp1 nfkb1 npnt ppp3ca slc39a8 tdrd7 tmod1 tspan5 xpa

Article Images: [+] show captions
References [+] :
, Sequence and comparative analysis of the chicken genome provide unique perspectives on vertebrate evolution. 2004, Pubmed

Xenbase: The Xenopus Model Organism Knowledgebase.
Version: 4.15.0
Major funding for Xenbase is provided by grant P41 HD064556