Three bovine  2-fucosyltransferase genes encode enzymes that preferentially transfer fucose on Gal 1-3GalNAc acceptor substrates

Abstract

To investigate the synthesis of alpha2-fucosylated epitopes in the bovine species, we have characterized cDNAs from various tissues. We found three distinct alpha2-fucosyltransferase genes, named bovine fut1, fut2, and sec1 which are homologous to human FUT1, FUT2, and Sec1 genes, respectively. Their open reading frames (ORF) encode polypeptides of 360 (bovine H), 344 (bovine Se), and 368 (bovine Sec1) amino acids, respectively. These enzymes transfer fucose in alpha1,2 linkage to ganglioside GM(1)and galacto- N -biose, but not to the phenyl-beta-D-galactoside, type 1 or type 2 acceptors, suggesting that their substrate specificity is different and more restricted than the other cloned mammalian alpha2-fucosyltransferases. Southern blot analyses detected four related alpha2-fucosyltransferase sequences in the bovine genome while only three have been described in other species. The supernumerary entity seems to be related to the alpha2-fucosyltransferase activity which can also use type 1 and phenyl-beta-D-galactoside substrate acceptors. It was exclusively found in bovine intestinal tract. Our results show that, at least in one mammalian species, four alpha2-fucosyltransferases are present, three adding a fucose on alpha1,2 linkage on type 3/4 acceptor (Galbeta1-3GalNAc) and another able to transfer also fucose on phenyl-beta-D-galactoside and type 1 (Galbeta1-3GlcNAc) acceptors. The phylogenetic tree of the enzymes homologous to those encoded by the bovine fut1, fut2, and sec1 genes revealed two main families, one containing all the H-like proteins and the second containing all the Se-like and Sec1-like proteins. The Sec1-like family had a higher evolutionary rate than the Se-like family.

Divergent evolution and purifying selection of the H (FUT1) gene in New World monkeys (Primates, Platyrrhini)

“…These results indicate, according to the relative rate test, that the H gene is evolving at a constant rate, both in the platyrrhines and in the order Primates. These values are in agreement with the suggestion of Barreaud et al (2000) and Bureau et al (2001), who observed that the evolution rate of H was intermediate among the α1,2 FT genes. This finding supports the hypothesis of selective pressure, given that selection, structural and functional requirements are the main factors which determine the evolution rate of a protein (Duret and Mouchiroud, 2000;Tourasse and Li, 2000).…”

“…This idea is supported by the mean similarity values of the platyrrhine nucleotide sequences and the human H genes, which are higher than those found between Se and Sec1 genes, and the presence of the three previously described conserved motifs (Figure 1), shared by all α1,2 fucosyltransferases studied so far (Breton et al, 1998;Oriol et al, 1999). The divergent evolution model proposed here is in agreement with the evolution model proposed by other studies that suggest that the common shared motifs represent evidence that the α1,2 fucosyltransferases, the H gene included, have a common genetic origin by duplication events, followed by divergent evolution of the species (Breton et al, 1998;Oriol et al, 1999;Barreaud et al, 2000;Bureau et al, 2001). …”

Evolution of the SEC1 gene in New World monkey lineages (Primates, Platyrrhini)

“…Apoil et al (2000) suggest that an Alu-like element inserted in a region crucial for regulation is responsible for expression of the H enzyme in human and ape erythroid lineages. The same was proposed for bovines and humans, in which SEC1 gene expression was detected only in intestinal tract cells (Barreaud et al, 2000). Table 3.…”

“…In humans, the erythrocytes (mesodermal origin) were the last cells to acquire the histo-blood group ABH antigens (Barreaud et al, 2000).…”

“…This gene also presents some characteristics of a non-autonomous retrotransposon, such as association with Alu-like elements and presence of a poly-A tail (Kelly et al, 1995;Saunier et al, 2001). On the other hand, Hitoshi et al (1995) and Barreaud et al (2000) showed that these three genes are fully activated in bovines and rabbits.…”