title: The Gal/GalNAc-specific lectin from the plant pathogenic basidiomycete Rhizoctonia solani is a member of the ricin-B family.
abstract: The lectin isolated from the phytopathogenic basidiomycete Rhizoctonia solani (RSA) is a homodimer of two noncovalently associated monomers of 15.5 kDa. RSA is a basic protein (pI > 9) which consists mainly of beta-sheets. A presumed relationship with ricin-B is supported by the sequence similarity between the N-terminus of RSA and the N-terminal subdomain of ricin-B. Hydrophobic cluster analysis confirms that the N-terminus of both proteins has a comparable folding. RSA exhibits specificity towards Gal/GalNAc whereby the hydroxyls at the C3', C4', and C6' positions of the pyranose ring play a key role in the interaction with simple sugars. The carbohydrate-binding site of RSA apparently accommodates only a single sugar unit. Our results demonstrate an obvious evolutionary relationship between some fungal and plant lectins, but also provide evidence for the occurrence of a lectin consisting of subunits corresponding to a single subdomain of ricin-B.
authors.affiliation: Institut de Pharmacologie et Biologie Structurale, UMR-CNRS 5089, 205 Route de Narbonne, Toulouse Cedex 4, 31077, France.
authors.forename: L
authors.initials: L
authors.lastname: Candy
authors.forename: W J
authors.initials: WJ
authors.lastname: Peumans
authors.forename: L
authors.initials: L
authors.lastname: Menu-Bouaouiche
authors.forename: C H
authors.initials: CH
authors.lastname: Astoul
authors.forename: J
authors.initials: J
authors.lastname: Van Damme
authors.forename: E J
authors.initials: EJ
authors.lastname: Van Damme
authors.forename: M
authors.initials: M
authors.lastname: Erard
authors.forename: P
authors.initials: P
authors.lastname: Rougé
mesh_terms: D000116:Acetylgalactosamine; D000595:Amino Acid Sequence; D001665:Binding Sites; D019281:Dimerization; D005690:Galactose; D007526:Isoelectric Point; D037102:Lectins / Q000737:chemistry* / Q000145:classification / Q000235:genetics / Q000302:isolation & purification; D008969:Molecular Sequence Data; D008970:Molecular Weight; D037121:Plant Lectins; D010944:Plants / Q000382:microbiology; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012232:Rhizoctonia / Q000737:chemistry* / Q000235:genetics / Q000472:pathogenicity; D012276:Ricin / Q000737:chemistry* / Q000145:classification / Q000235:genetics; D017386:Sequence Homology, Amino Acid
chemical_list: D037102:Lectins; D037121:Plant Lectins; D012276:Ricin; D000116:Acetylgalactosamine; D005690:Galactose