title: Mapping glycans onto specific N-linked glycosylation sites of Pyrus communis PGIP redefines the interface for EPG-PGIP interactions.
abstract: Polygalacturonase inhibiting proteins (PGIPs) are members of the leucine rich repeat family of proteins, involved in plant defense against fungal pathogens. PGIPs exhibit a remarkable degree of specificity in terms of their ability to bind and inhibit their target molecules, the endopolygalacturonases (EPGs). This specificity has been attributed for certain EPG/PGIP combinations to differences in primary sequence, but this explanation is unable to account for the full range of binding and inhibitory activities observed. In this paper, we have fully characterized the glycosylation on the PGIP derived from Pyrus communis and demonstrated, using a combination of PNGaseF and PNGaseA in (18)O-water, that the Pyrus communis PGIP utilizes all seven potential sites of N-linked glycosylation. Further, we demonstrate that certain sites appear to be modified only by glycans bearing alpha3-linked core fucosylation, while others are occupied by a mixture of fucosylated and nonfucosylated glycans. Modeling of the carbohydrates onto a homologous structure of PGIP indicates potential roles for glycosylation in mediating the interactions of PGIPs with EPGs.
authors.affiliation: Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA.
authors.forename: Jae-Min
authors.initials: JM
authors.lastname: Lim
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Aoki
authors.forename: Peggi
authors.initials: P
authors.lastname: Angel
authors.forename: Derek
authors.initials: D
authors.lastname: Garrison
authors.forename: Daniel
authors.initials: D
authors.lastname: King
authors.forename: Michael
authors.initials: M
authors.lastname: Tiemeyer
authors.forename: Carl
authors.initials: C
authors.lastname: Bergmann
authors.forename: Lance
authors.initials: L
authors.lastname: Wells
mesh_terms: D000935:Antifungal Agents / Q000737:chemistry / Q000378:metabolism; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D006031:Glycosylation; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism; D011096:Polygalacturonase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011134:Polysaccharides / Q000032:analysis*; D011487:Protein Conformation; D031989:Pyrus / Q000737:chemistry / Q000201:enzymology
chemical_list: D000935:Antifungal Agents; C081479:PGIP protein, plant; D010940:Plant Proteins; D011134:Polysaccharides; D011096:Polygalacturonase