title: Structure and distribution of N-glycans on the S7-allele stylar self-incompatibility ribonuclease of Nicotiana alata.
abstract: S-RNases are the stylar products of the self-incompatibility (S)-locus in solanaceous plants (including Nicotiana alata), and as such, are involved in the prevention of self-pollination. All cDNA sequences of S-RNase products of functional S-alleles contain potential N-glycosylation sites, with one site being conserved in all cases, suggesting that N-glycosylation is important in self-incompatibility. In this study, we report on the structure and localization of the N-glycans on the S7-allele RNase of N. alata. A total of nine N-glycans, belonging to the high-mannose- and xylosylated hybrid-classes, were identified and characterized by a combination of electrospray-ionization mass-spectrometry (ESI-MS), 1H-NMR spectroscopy, and methylation analyses. The glycosylation pattern of individual glycosylation sites was determined by ESI-MS of the glycans released from isolated chymotryptic glycopeptides. All three N-glycosylation sites showed microheterogeneity and each had a unique complement of N-glycans. The N-glycosylation pattern of the S7-RNase is significantly different to those of the S1- and S2-RNases.
authors.affiliation: Plant Cell Biology Research Centre, School of Botany, University of Melbourne, Parkville, Victoria 3052, Australia. d.oxley@botany.unimelb.edu.au
authors.forename: D
authors.initials: D
authors.lastname: Oxley
authors.forename: S L
authors.initials: SL
authors.lastname: Munro
authors.forename: D J
authors.initials: DJ
authors.lastname: Craik
authors.forename: A
authors.initials: A
authors.lastname: Bacic
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D002240:Carbohydrate Sequence; D002851:Chromatography, High Pressure Liquid; D006031:Glycosylation; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D010947:Plants, Toxic; D011134:Polysaccharides / Q000737:chemistry*; D012260:Ribonucleases / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D014026:Nicotiana / Q000201:enzymology* / Q000235:genetics
chemical_list: D010940:Plant Proteins; D011134:Polysaccharides; D012260:Ribonucleases