The presence of Lewis a epitopes in Arabidopsis thaliana glycoconjugates depends on an active alpha4-fucosyltransferase gene.
The presence of an alpha4-fucosyltransferase in plants was first deduced from the characterization of Lewis-a glycoepitopes in some N-glycans. The first plant gene encoding an alpha4-fucosyltransferase was recently cloned in Beta vulgaris. In the present paper we provide evidence for the presence of an alpha4-fucosyltransferase in A. thaliana by measurement of this glycosyltransferase activity from a purified microsomal preparation and by immunolocalization of Le(a) epitopes on glycans N-linked to glycoproteins located to the Golgi apparatus and on the cell surface. The corresponding gene AtFT4 (AY026941) was characterized. A unique copy of this gene was found in A. thaliana genome, and a single AtFT4 transcript was revealed in leaves, in roots, and at a lower extent in flowers. The coding sequence of AtFT4 gene is interrupted by two introns spanning 465 bp and 84 bp, respectively. The putative 393-amino-acid protein (44 kDa, pI: 6.59) contains an N-terminal hydrophobic region and one potential N-glycosylation site, but AtFT4 has poor homology (less than 30%) to the other alpha3/4-fucosyltransferases except for motif II. When expressed in COS 7 cells the protein is able to transfer Fuc from GDP-Fuc to a type 1 acceptor substrate, but this transferase activity is detected only in the culture medium of transfected cells
Léonard
R
R
Equipe de Glycobiologie et Biotechnologie (EA 3176), Institut des Sciences de la Vie et de la Santé, Université de Limoges, Faculté des Sciences, 123, Avenue Albert Thomas, 87060 Limoges, France.
Costa
G
G
Darrambide
E
E
Lhernould
S
S
Fleurat-Lessard
P
P
Carlué
M
M
Gomord
V
V
Faye
L
L
Maftah
A
A
D000595:Amino Acid Sequence; D000941:Antigens / Q000737:chemistry*; D017360:Arabidopsis / Q000737:chemistry* / Q000201:enzymology / Q000235:genetics; D001483:Base Sequence; D015152:Blotting, Northern; D015139:Blotting, Southern; D003001:Cloning, Molecular; D018076:DNA, Complementary; D000939:Epitopes / Q000737:chemistry*; D005647:Fucosyltransferases / Q000737:chemistry / Q000235:genetics*; D006001:Glycoconjugates / Q000737:chemistry* / Q000276:immunology; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000235:genetics; D017386:Sequence Homology, Amino Acid
D000941:Antigens; D018076:DNA, Complementary; D000939:Epitopes; D006001:Glycoconjugates; D012333:RNA, Messenger; D005647:Fucosyltransferases; C019818:3-galactosyl-N-acetylglucosaminide 4-alpha-L-fucosyltransferase