Characterization of bovine FUT7 furthers understanding of FUT7 evolution in mammals.
BACKGROUND
The Sialyl-Lewis X (Slex) is a well-known glycan structure involved in leukocyte homing and recruitment to inflammatory sites. SLex is well conserved among species and is mainly synthesized by FucT-VII in vertebrates. The enzyme responsible for its biosynthesis in cattle was not known.


RESULTS
We cloned a cDNA sequence encoding bovine α3-fucosyltransferase VII that shares 83% identity with its human counterpart. Located at the BTA 11 telomeric region, the 1029 bp open reading frame is spread over two different exons, E1 which also contains the unique 5'-untranslated region and E2 which includes the entire 3'-untranslated region. The bfut7 expression pattern is restricted to thymus and spleen. A single transcript leading to the synthesis of a 342 aa protein was identified. The encoded fucosyltransferase, produced as a recombinant enzyme in COS-1 cells, was shown to be specifically responsible for SLex synthesis in cattle. In addition, we showed that the gene promoter evolved from fish to mammals towards a complex system related to the immune system. But beyond the fact that the gene regulation seems to be conserved among mammals, we also identified 7 SNPs including 3 missense mutations in the coding region in a small panel of animals.


CONCLUSIONS
The FUT7 sequence was highly conserved as well as the specific activity of the encoded protein FucT-VII. In addition, our in silico promoter analysis and the high rate of polymorphism suggested that its function is evolving toward a complex system related to the immune system. Furthermore, comparing bovine to human and mouse sequences, it appeared that a decrease in gene regulation was correlated with an increase in mutation rate and wider tissue expression.
INRA UMR 1061, Unité de Génétique Moléculaire Animale, Université de Limoges, Faculté des Sciences et Techniques, 123 Avenue A, Thomas, Limoges 87060, France.
Benoît
B
Laporte
Daniel
D
Petit
Dominique
D
Rocha
Mekki
M
Boussaha
Cécile
C
Grohs
Abderrahman
A
Maftah
Jean-Michel
JM
Petit
D020413:3' Untranslated Regions; D020121:5' Untranslated Regions; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D019556:COS Cells; D002417:Cattle; D002522:Chlorocebus aethiops; D019143:Evolution, Molecular; D005091:Exons; D005647:Fucosyltransferases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D007107:Immune System / Q000378:metabolism; D008322:Mammals / Q000235:genetics; D051379:Mice; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D009844:Oligosaccharides / Q000737:chemistry; D020641:Polymorphism, Single Nucleotide; D011401:Promoter Regions, Genetic; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D000080506:Sialyl Lewis X Antigen; D014157:Transcription Factors / Q000378:metabolism
D020413:3' Untranslated Regions; D020121:5' Untranslated Regions; D009844:Oligosaccharides; D011994:Recombinant Proteins; D000080506:Sialyl Lewis X Antigen; D014157:Transcription Factors; D005647:Fucosyltransferases