Processing of N-linked oligosaccharides from precursor- to mature-form herpes simplex virus type 1 glycoprotein gC.
Immature and mature forms of glycoprotein gC were purified by immunoadsorbent from herpes simplex virus type 1-infected BHK cells labeled with [3H]mannose for a 20-min pulse or for 11 h followed by a 3-h chase. The nature of N-asparagine-linked oligosaccharides carried by the immature form, pgC (molecular weight = 92,000), and the mature gC (molecular weight = 120,000) has been investigated. All pronase-digested glycopeptides of pgC were susceptible to endo-beta-N-acetylglucosaminidase H treatment; thus they have a high-mannose structure. Using thin-layer chromatography to separate endo-beta-N-acetylglucosaminidase H-cleaved oligosaccharides, polymannosyl chains of different sizes, ranging from Man9GlcNAc to Man5GlcNAc, were separated. The major components were Man8GlcNAc and Man7GlcNAc, suggesting that pgC labeled in a 20-min pulse represents the form of glycoprotein already routed to the Golgi apparatus. Analysis of glycopeptides of mature gC showed that the majority (95%) of N-linked glycans were converted to complex-type glycans. Ion-exchange chromatography and affinity chromatography on concanavalin A-Sepharose and leucoagglutinin-agarose revealed that diantennary and triantennary glycans predominated, whereas tetrantennary chains were not present. Parts of the di- and triantennary chains were not fully sialylated. The high heterogeneity of complex-type chains found in mature gC may be related to the high number of N-glycosylation sites of the glycoprotein as predicted by DNA sequencing studies (Frink et al., J. Virol. 45:634-647, 1983).
D000818:Animals; D002460:Cell Line; D002846:Chromatography, Affinity; D006224:Cricetinae; D006020:Glycopeptides / Q000032:analysis; D007668:Kidney; D008358:Mannose / Q000032:analysis; D008970:Molecular Weight; D009844:Oligosaccharides / Q000378:metabolism*; D011402:Pronase; D011499:Protein Processing, Post-Translational; D018139:Simplexvirus / Q000235:genetics*; D014759:Viral Envelope Proteins; D014764:Viral Proteins / Q000235:genetics* / Q000302:isolation & purification
D006020:Glycopeptides; D009844:Oligosaccharides; D014759:Viral Envelope Proteins; D014764:Viral Proteins; C038535:glycoprotein gC, herpes simplex virus type 1; D011402:Pronase; D008358:Mannose