A novel alpha1,2-fucosyltransferase (CE2FT-2) in Caenorhabditis elegans generates H-type 3 glycan structures

The alpha1,2-fucosyltransferase family (alpha1,2FT) is the largest family of glycosyltransferases in the genome of the free-living nematode Caenorhabditis elegans, and early evidence suggests that each member may have a unique activity. Here we describe a C. elegans gene (designated CE2FT-2) encoding an alpha1,2FT that has the potential to generate the sequence Fucalpha1-2Galbeta1-3GalNAcalpha-R, which is the H-type 3 blood group structure. The CE2FT-2 cDNA encodes a putative transmembrane protein that shows approximately 42% amino acid identity to a previously cloned C. elegans alpha1,2FT (termed CE2FT-1), but has a very low identity ( approximately 16-20%) to alpha1,2FT sequences in humans, rabbits, and mice. A recombinant form of CE2FT-2 expressed in human 293T cells has a high alpha1,2FT activity toward Galbeta1-3GalNAcalpha-O-pNP, but unexpectedly, the enzyme is inactive toward the acceptor Galbeta-O-phenyl. Thus, CE2FT-2 differs from all other alpha1,2FTs previously described from animals that all utilize Galbeta-O-phenyl. CE2FT-2 is expressed at all stages of worm development, but remarkably, promoter analysis of the CE2FT-2 gene using green fluorescent protein reporter constructs indicates that the CE2FT-2 is expressed exclusively in pharyngeal cells of the worm from embryo to an adult stage. Because pharyngeal cells are known to secrete their glycoconjugates to the nematode surface, these results may indicate that products of CE2FT-2 contribute to interactions of the nematode with its environment or are used as ligands for bacterial attachment. These findings, along with those on other alpha1,2FTs in C. elegans, suggest that each alpha1,2FT in this organism may have a unique acceptor specificity, expression pattern, and biological function.