Differential effects of oncogenic transformation on N-linked oligosaccharide processing at individual glycosylation sites of viral glycoproteins.
Hamster sarcoma virus (HSV) transformation of Nil-8 fibroblasts is associated with an increase in the average size of N-acetyllactosamine (complex) type N-linked glycans due to an increase in both the average number of branches/chain and in the fraction of N-linked glycans containing poly(GlcNAc(beta 1,3) Gal-(beta 1,4)) (polylactosaminylglycan) chains. Analysis of glycopeptides from the envelope glycoproteins of Sindbis virus and vesicular stomatitis virus (VSV) grown in Nil-8 and Nil/HSV cells indicated that the transformation-associated shift to larger N-linked oligosaccharides selectively affects some glycosylation sites far more than others. Glycosylation of the Sindbis virus glycoproteins and of Asn-179 of VSV G was similar in Nil-8 and Nil/HSV cells; oligosaccharide processing generally did not proceed beyond the biantennary complex stage. In contrast, Asn-336 of VSV G carried primarily biantennary complex glycans in Nil-8-grown virus (ratio, triantennary, and larger to biantennary complex glycans (tri+/bi) = 0.5) but more highly branched structures in Nil/HSV-grown virus (tri+/bi = 8.1). All of the triantennary or larger oligosaccharides from Asn-336 of Nil/HSV-grown VSV G bound to leukoagglutinating phytohemagglutinin-agarose, indicating the presence of a branch attached to the Man3GlcNAc2 core via a beta 1,6-linked GlcNAc residue and suggesting that increased UDP-GlcNAc:alpha-D-mannoside beta 1,6-N-acetylglucosaminyl transferase V (GlcNAc transferase V) activity accompanied transformation. At least 20% of these leukoagglutinating phytohemagglutinin-binding oligosaccharides were sensitive to an enzyme specific for polylactosaminylglycan chains, Escherichia freundii endo-beta-galactosidase.
Hubbard
S C
SC
Center for Cancer Research, Massachusetts Institute of Technology, Cambridge 02139.
D000818:Animals; D002240:Carbohydrate Sequence; D002460:Cell Line; D002471:Cell Transformation, Neoplastic; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D006023:Glycoproteins / Q000378:metabolism*; D006031:Glycosylation; D006596:Hexosaminidases / Q000378:metabolism; D009844:Oligosaccharides / Q000378:metabolism*; D009857:Oncogenes; D011402:Pronase / Q000378:metabolism; D009053:Sarcoma Viruses, Murine / Q000378:metabolism*
D006023:Glycoproteins; D009844:Oligosaccharides; D006596:Hexosaminidases; D011402:Pronase