Glycobiology Advance Access originally published online on February 13, 2007
Glycobiology 2007 17(5):516-528; doi:10.1093/glycob/cwm016
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Long-term evolution of the CAZY glycosyltransferase 6 (ABO) gene family from fishes to mammals—a birth-and-death evolution model
2 INSERM U601, Université de Nantes, Institut de Biologie, 9 Quai Moncousu, 44093 Nantes Cedex, France
3 Laboratoire d'Immunogénétique Moléculaire, Université Paul Sabatier, CHU de Toulouse, Laboratoire d'Immunologie, Hôpital Rangueil, TSA 50032, 31059 Toulouse Cedex 9, France
4 L'Etablissement Français Sang Centre Atlantique, 2 Boulevard Tonnellé, Box 52009, 37020 Tours Cedex 1, France
5 Shemyakin Institute for Bioorganic Chemistry, 117871 Moscow, Russia
1 To whom correspondence should be addressed; Tel: +33 5 61 32 34 34; Fax: +33 5 61 32 34 24; e-mail: blancher.a{at}chu-toulouse.fr
Received on December 15, 2006; revised on February 3, 2007; accepted on February 3, 2007
Functional glycosyltransferase 6 (GT6) family members catalyze the transfer of galactose or N-acetylgalactosamine in 
1,3 linkage to various substrates and synthesize structures related to the A and B histo-blood group antigens, the Forssman antigen, Gal epitope, and iGb3 glycolipid. In rat, mouse, dog, and cow genomes, we have identified three new mammalian genes (GT6m5, GT6m6, and GT6m7) encoding putative proteins belonging to the GT6 family. Among these, GT6m6 protein does not display major alterations of the GT6 motifs involved in binding of the divalent cation and the substrate. Based on protein sequence comparison, gene structure, and synteny, GT6 homologous sequences were also identified in bird, fish, and amphibian genomes. Strikingly, the number and type of GT6 genes varied widely from species to species, even within phylogenetically related groups. In human, except ABO functional alleles, all other GT6 genes are either absent or nonfunctional. Human, mouse, and cow have only one ABO gene, whereas rat and dog have several. In the chicken, the Forssman synthase-like is the single GT6 family member. Five Forssman synthase-like genes were found in zebrafish, but are absent from three other fishes (fugu, puffer fish, and medaka). Two iGb3 synthase-like genes were found in medaka, which are absent from zebrafish. Fugu, puffer fish, and medaka have an additional GT6 gene that we termed GT6m8, which is absent from all other species analyzed here. These observations indicate that individual GT6 genes have expanded and contracted by recurrent duplications and deletions during vertebrate evolution, following a birth-and-death evolution type.
Key words: ABO / birth-and-death / evolution / glycosyltransferase / histo-blood group