Changes in N-linked oligosaccharides during seed development of Ginkgo biloba.
Structural changes in N-linked oligosaccharides of glycoproteins during seed development of Ginkgo biloba have been explored to discover possible endogenous substrate(s) for the Ginko endo-beta-N-acetylglucosaminidase (endo-GB; Kimura, Y., et al. (1998) Biosci. Biotechnol. Biochem., 62, 253-261), which should be involved in the production of high-mannose type free N-glycans. The structural analysis of the pyridylaminated oligosaccharides with a 2D sugar chain map, by ESI-MS/MS spectroscopy, showed that all N-glycans expressed on glycoproteins through the developmental stage of the Ginkgo seeds have the xylose-containing type (GlcNAc2 approximately 0Man3Xyl1Fuc1 approximately 0GlcNAc2) but no high-mannose type structure. Man3Xyl1Fuc1GlcNAc2, a typical plant complex type structure especially found in vacuolar glycoproteins, was a dominant structure through the seed development, while the amount of expression of GlcNAc2Man3Xyl1Fuc1GlcNAc2 and GlcNAc1Man3Xyl1Fuc1GlcNAc2 decreased as the seeds developed. The dominantly occurrence of xylose-containing type structures and the absence of the high-mannose type structures on Ginkgo glycoproteins were also shown by lectin-blotting and immunoblotting of SDS-soluble glycoproteins extracted from the developing seeds at various developmental stages. Concerning the endogenous substrates for plant endo-beta-N-acetylglucosaminidase, these results suggested that the endogenous substrates might be the dolicol-oligosaccharide intermediates or some glycopeptides with the high-mannose type N-glycan(s) derived from misfolded glycoproteins in the quality control system for newly synthesized glycoproteins.
Kimura
Y
Y
Department of Bioresources Chemistry, Faculty of Agriculture, Okayama University, Japan. yosh8mar@cc.okayama-u.ac.jp
Matsuo
S
S
D002240:Carbohydrate Sequence; D020441:Ginkgo biloba / Q000254:growth & development / Q000378:metabolism*; D006023:Glycoproteins / Q000378:metabolism; D015151:Immunoblotting / Q000379:methods; D037102:Lectins / Q000378:metabolism; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000378:metabolism*; D037121:Plant Lectins; D010940:Plant Proteins / Q000378:metabolism; D010946:Plants, Medicinal; D011134:Polysaccharides / Q000032:analysis; D012639:Seeds / Q000737:chemistry / Q000254:growth & development; D012967:Sodium Dodecyl Sulfate; D012995:Solubility
D006023:Glycoproteins; D037102:Lectins; D009844:Oligosaccharides; D037121:Plant Lectins; D010940:Plant Proteins; D011134:Polysaccharides; D012967:Sodium Dodecyl Sulfate