title: Exquisite binding specificity of Sclerotium rolfsii lectin toward TF-related O-linked mucin-type glycans.
abstract: Sclerotium rolfsii lectin (SRL), a secretory protein from the soil borne phytopathogenic fungus Sclerotium rolfsii, has shown in our previous studies to bind strongly to the oncofetal Thomson-Friedenreich carbohydrate (Galβ1-3GalNAc-ser/thr, T or TF) antigen. TF antigen is widely expressed in many types of human cancers and the strong binding of SRL toward such a cancer-associated carbohydrate structure led us to characterize the carbohydrate binding specificity of SRL. Glycan array analysis, which included 285 glycans, shows exclusive binding of SRL to the O-linked mucin type but not N-linked glycans and amongst the mucin type O-glycans, lectin recognizes only mucin core 1, core 2 and weakly core 8 but not to other mucin core structures. It binds with high specificity to "α-anomers" but not the "β-anomers" of the TF structure. The axial C4-OH group of GalNAc and C2-OH group of Gal is both essential for SRL interaction with TF disaccharide, and substitution on C3 of galactose by sulfate or sialic acid or N-acetylglucosamine, significantly enhances the avidity of the lectin. SRL differs in its binding to TF structures compared to other known TF-binding lectins such as the Arachis hypogea (peanut) agglutinin, Agaricus bisporus (mushroom) lectin, Jackfruit, Artocarpus integrifolia (jacalin) and Amaranthus caudatus (Amaranthin) lectin. Thus, SRL has unique carbohydrate-binding specificity toward TF-related O-linked carbohydrate structures. Such a binding specificity will make this lectin a very useful tool in future structural as well as functional analysis of the cellular glycans in cancer studies.
authors.affiliation: P.G. Department of Studies in Biochemistry, Karnatak University, Dharwad, 580 003, India.
authors.forename: Vishwanath B
authors.initials: VB
authors.lastname: Chachadi
authors.forename: Shashikala R
authors.initials: SR
authors.lastname: Inamdar
authors.forename: Lu-Gang
authors.initials: LG
authors.lastname: Yu
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Rhodes
authors.forename: Bale M
authors.initials: BM
authors.lastname: Swamy
mesh_terms: D001487:Basidiomycota / Q000378:metabolism*; D001710:Biotin / Q000378:metabolism; D002240:Carbohydrate Sequence; D037102:Lectins / Q000378:metabolism*; D008969:Molecular Sequence Data; D009077:Mucins / Q000378:metabolism*; D011134:Polysaccharides / Q000378:metabolism*; D011485:Protein Binding
chemical_list: D037102:Lectins; D009077:Mucins; D011134:Polysaccharides; D001710:Biotin