The Drosophila melanogaster homologue of the human histo-blood group Pk gene encodes a glycolipid-modifying α1,4- N -acetylgalactosaminyltransferase

• Published in: Biochemical journal 2004-08, Vol.382 (1), p.67-74
• Main Authors: MUCHA, Ján, DOMLATIL, Jiří, LOCHNIT, Günter, RENDIĆ, Dubravko, PASCHINGER, Katharina, HINTERKÖRNER, Georg, HOFINGER, Andreas, KOSMA, Paul, WILSON, Iain B. H.
• Format: Article
• Language: English
• ISSN: 0264-6021; 1470-8728
• DOI: 10.1042/BJ20040535

Insects express arthro-series glycosphingolipids, which contain an α1,4-linked GalNAc residue. To determine the genetic basis for this linkage, we cloned a cDNA (CG17223) from Drosophila melanogaster encoding a protein with homology to mammalian α1,4-glycosyltransferases and expressed it in the yeast Pichia pastoris. Culture supernatants from the transformed yeast were found to display a novel UDP-GalNAc:GalNAcβ1,4GlcNAcβ1-R α-N-acetylgalactosaminyltransferase activity when using either a glycolipid, p-nitrophenylglycoside or an N-glycan carrying one or two terminal β-N-acetylgalactosamine residues. NMR and MS in combination with glycosidase digestion and methylation analysis indicate that the cloned cDNA encodes an α1,4-N-acetylgalactosaminyltransferase. We hypothesize that this enzyme and its orthologues in other insects are required for the biosynthesis of the N5a and subsequent members of the arthro-series of glycolipids as well as of N-glycan receptors for Bacillus thuringiensis crystal toxin Cry1Ac.