title: Ascidian and amphioxus Adh genes correlate functional and molecular features of the ADH family expansion during vertebrate evolution.
abstract: The alcohol dehydrogenase (ADH) family has evolved into at least eight ADH classes during vertebrate evolution. We have characterized three prevertebrate forms of the parent enzyme of this family, including one from an urochordate (Ciona intestinalis) and two from cephalochordates (Branchiostoma floridae and Branchiostoma lanceolatum). An evolutionary analysis of the family was performed gathering data from protein and gene structures, exon-intron distribution, and functional features through chordate lines. Our data strongly support that the ADH family expansion occurred 500 million years ago, after the cephalochordate/vertebrate split, probably in the gnathostome subphylum line of the vertebrates. Evolutionary rates differ between the ancestral, ADH3 (glutathione-dependent formaldehyde dehydrogenase), and the emerging forms, including the classical alcohol dehydrogenase, ADH1, which has an evolutionary rate 3.6-fold that of the ADH3 form. Phylogenetic analysis and chromosomal mapping of the vertebrate Adh gene cluster suggest that family expansion took place by tandem duplications, probably concurrent with the extensive isoform burst observed before the fish/tetrapode split, rather than through the large-scale genome duplications also postulated in early vertebrate evolution. The absence of multifunctionality in lower chordate ADHs and the structures compared argue in favor of the acquisition of new functions in vertebrate ADH classes. Finally, comparison between B. floridae and B. lanceolatum Adhs provides the first estimate for a cephalochordate speciation, 190 million years ago, probably concomitant with the beginning of the drifting of major land masses from the Pangea.
authors.affiliation: Departament de Genètica, Facultat de Biologia, Universitat de Barcelona, Av. Diagonal 645, E-08028 Barcelona, Spain.
authors.forename: Cristian
authors.initials: C
authors.lastname: Cañestro
authors.forename: Ricard
authors.initials: R
authors.lastname: Albalat
authors.forename: Lars
authors.initials: L
authors.lastname: Hjelmqvist
authors.forename: Laura
authors.initials: L
authors.lastname: Godoy
authors.forename: Hans
authors.initials: H
authors.lastname: Jörnvall
authors.forename: Roser
authors.initials: R
authors.lastname: Gonzàlez-Duarte
mesh_terms: D000426:Alcohol Dehydrogenase / Q000235:genetics*; D019943:Amino Acid Substitution; D000818:Animals; D002816:Chordata, Nonvertebrate / Q000235:genetics*; D019143:Evolution, Molecular; D005091:Exons; D020440:Gene Duplication; D007438:Introns; D005810:Multigene Family; D010802:Phylogeny; D020033:Protein Isoforms; D017422:Sequence Analysis, DNA; D020080:Tandem Repeat Sequences; D014561:Urochordata / Q000235:genetics*; D014714:Vertebrates / Q000235:genetics
chemical_list: D020033:Protein Isoforms; D000426:Alcohol Dehydrogenase