Evidence for New β1-3 Galactosyltransferase Activity Involved in Biosynthesis of UnusualN-Glycan Harboring T-Antigen inApis mellifera

Abstract

In a previous study (Y. Kimura et al., Biosci. Biotechnol. Biochem., 70, 2583-2587, 2006), we found that new complex type N-glycans harboring Thomsen-Friedenreich antigen (Galbeta1-3GalNAc) unit occur on royal jelly glycoproteins, suggesting the involvement of a new beta1-3galactosyltransferase in the synthesis of the unusual complex type N-glycans. So far, such beta1-3galactosyltransferase activity, which can transfer galactosyl residues with the beta1-3 linkage to beta1-4 GalNAc residues in N-glycan, has not been found among any eucaryotic cells. But using GalNAc(2)GlcNAc(2)Man(3)GlcNAc(2)-PA as acceptor N-glycan, we detected the beta1-3 galactosyltransferase activity in membrane fraction prepared from honeybee cephalic portions. This result indicates that honeybee expresses a unique beta1-3 galactosyltransferase involved in biosynthesis of the unusual N-glycan containing a tumor related antigen in the hypopharyngeal gland.

Targeted release and fractionation reveal glucuronylated and sulphated N- and O-glycans in larvae of dipteran insects

“…The Galβ1,3GalNAcβ1,4GlcNAc motif, which appears to constitute the antennae for some of the glucuronylated glycans described here, has been previously found in unglucuronylated form as a ‘T-antigen’ on biantennary N-glycans from honeybee royal jelly [57], whereas GalNAcβ1,4GlcNAc is found in fucosylated form on honeybee venom glycoproteins [58]. Relevant β1,3-galactosyltransferase and β1,4- N -acetylgalactosaminyltransferase enzymes have been described from insect sources [59-62]. The occurrence of terminal galactose on N-glycans and its assumed presence on O-glycans ( e.g., the core 1 type) is also of interest as Aedes larvae are sensitive to a number of fungal lectins which bind galactose, N -acetylgalactosamine or fucose residues [63].…”

Phenotype‐based clustering of glycosylation‐related genes by RNAi‐mediated gene silencing

“…(Kimura et al . 2006, 2007). Thus, we examined whether CG33145 added Gal to GalNAcβ1,4GlcNAcβ1,2Manα1,6(GalNAcβ1,4GlcNAcβ1,2Manα1,3)Manβ1,4GlcNAcβ1,4GlcNAc (E2, Fig 7A…”

“…The acceptor substrate E2 and standards, E4 and E5, were prepared as described previously (Kimura et al . 2006, 2007). Enzymatic reactions, product detection, and product confirmation were also carried out as noted previously (Kimura et al .…”

“…Enzymatic reactions, product detection, and product confirmation were also carried out as noted previously (Kimura et al . 2006, 2007). …”

Identification of a Royal Jelly Glycoprotein That Carries Unique Complex-Type N-Glycans Harboring the T-Antigen (Galβ1-3GalNAc) Unit

“…Furthermore, we confirmed the occurrence of 1-3GalT activity in the microsomal fraction prepared from the cephalic portion of the honeybee. 2) However, at present time, it remains to be determined what royal jelly glycoproteins bear the new complex-type royal jelly N-glycans harboring the T-antigen unit. As a first step to reveal the physiological significance of this complex-type N-glycan, identification of the glycoproteins having the honeybee specific N-glycans and the glycosylation site is prerequisite.…”