Comparison of the three rat GDP‐L‐fucose:β‐D‐galactoside 2‐α‐L‐fucosyltransferases FTA, FTB and FTC

Abstract

The complete coding sequences of three rat a1,2fucosyl-transferase genes were obtained. Sequence analysis revealed that these genes, called FTA, FTB and FTC, were homologous to human FUT1, FUT2 and Sec1, respectively. A distance analysis between all a1,2fucosyl-transferase sequences available showed that the two domains of the catalytic region evolved differently with little divergence between the FUT2 and Sec1 N-terminal domains, quite distant from that of FUT1. At variance, FUT1 and FUT2 C-terminal domains were less distant while a high evolutionary rate was noted for Sec1 C-terminal domain. Whereas FTA and FTB encode typical glycosyltransferases, FTC lacks the homologous start codon and encodes a protein devoid of intracellular and transmembrane domains. It is located on rat chromosome 1q34. Transfection experiments revealed that unlike FTA and FTB, FTC does not generate enzyme activity. Analysis by flow cytometry showed that H type 2 epitopes were synthesized in Chinese hamster ovary cells transfected by both FTA and FTB cDNA, but only FTB transfectants possessed H type 3 determinants. In REG rat carcinoma cells, both FTA and FTB allowed synthesis of H type 2 and H type 3 at the cell surface. Western blots showed that, in both cell types, FTA was able to synthesize H type 2 epitopes on a larger set of glycoproteins than FTB. Analysis of the kinetic parameters obtained using small oligosaccharides revealed only a slight preference of FTA for type 2 over other types of acceptor substrates, whereas FTB was barely able to fucosylate this substrate.

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)

“…The transition/transversion rates and nucleotide sequence alignment support the hypothesis that primate SEC1 evolved by divergent evolution, as proposed for the origin of fucosyltransferases (Breton et al, 1998;Oriol et al, 1999;Barreaud et al, 2000;Bureau et al, 2001;Borges and Harada, 2004). In contrast, multiple stop codons and amino acid changes present in different species suggest convergent inactivation events in apes, Callitrichinae, Aotus and Pithecia.…”

Cell Surface Fucosylation Does Not Affect Development of Colon Tumors in Mice with Germline Smad3 Mutation

“…Fut1 and Fut2 enzymes can ␣ (1,2)fucosylate a variety of glycans and glycolipids. In enzymic studies with natural and synthetic substrates, both enzymes were shown to be capable of adding ␣ (1,2)fucose to both H antigen type 1 and type 2 acceptor substrates but with differing enzymatic kinetic parameters [13,32] . In pancreatic cancer cells, studies have postulated that increased ␣ (1,2)fucosylation reduce metastatic potential by decreasing the adhesive properties due to altered sialyl Lewis antigen presented at the cell surface [33] .…”