Fuc-TIX: a versatile alpha1,3-fucosyltransferase with a distinct acceptor- and site-specificity profile.
alpha1,3-Fucosyltransferases (Fuc-Ts) convert N-acetyllactosamine (LN, Galbeta1-4GlcNAc) to Galbeta1-4(Fucalpha1-3)GlcNAc, the Lewis x (CD15, SSEA-1) epitope, which is involved in various recognition phenomena. We describe details of the acceptor specificity of alpha1,3-fucosyltransferase IX (Fuc-TIX). The unconjugated N- and O-glycan analogs LNbeta1-2Man, LNbeta1-6Manalpha1-OMe, LNbeta1-2Manalpha1-3(LNbeta1-2Manalpha1-6)Manbeta1-4GlcNAc, and Galbeta1-3(LNbeta1-6)GalNAc reacted well in vitro with Fuc-TIX present in lysates of appropriately transfected Namalwa cells. Fuc-TIX reacted well with the reducing end LN of GlcNAcbeta1-3'LN (underscored site reacted) and GlcNAcbeta1-3'LNbeta1-3'LN (both LNs reacted), but very poorly with the reducing end LN of LNbeta1-3'LN. However, Fuc-TIX reacted significantly better with the non-reducing end LN as compared to the other LN units in the glycans LNbeta1-3'LN and LNbeta1-3'LNbeta1-3'LNbeta1-3'LN, confirming our previous data on LNbeta1-3'LNbeta1-OR. In contrast, the sialylated glycan Neu5Acalpha2-3'LNbeta1-3'LNbeta1-3'LNbeta1-3'LN was fucosylated preferentially at the two most reducing end LN units. We conclude that Fuc-TIX is a versatile alpha1,3-Fuc-T, that (1) generates distal Lewis x epitopes from many different acceptors, (2) possesses inherent ability for the biosynthesis of internal Lewis x epitopes on growing polylactosamine backbones, and (3) fucosylates the remote internal LN units of alpha2,3-sialylated i-type polylactosamines.
Toivonen
Suvi
S
Institute of Biotechnology and Department of Biosciences, University of Helsinki, P.O. Box 56, 00014 Helsinki, Finland.
Nishihara
Shoko
S
Narimatsu
Hisashi
H
Renkonen
Ossi
O
Renkonen
Risto
R
D000606:Amino Sugars / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D002240:Carbohydrate Sequence; D002460:Cell Line; D006224:Cricetinae; D004187:Disaccharides / Q000378:metabolism; D005647:Fucosyltransferases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D011134:Polysaccharides / Q000378:metabolism*; D013379:Substrate Specificity; D014312:Trisaccharides / Q000378:metabolism
D000606:Amino Sugars; D004187:Disaccharides; D011134:Polysaccharides; D014312:Trisaccharides; C066929:polylactosamine; D005647:Fucosyltransferases; C031692:galactoside 3-fucosyltransferase