A Comparison of the Fine Saccharide‐Binding Specificity of Dioclea grandiflora Lectin and Concanavalin A

Abstract

The lectin from the seeds of Dioclea grandifora (DGL) is a Man/Glc-specific tetrameric protein with physical and saccharide-binding properties reported to be similar to that of the jack bean lectin concanavalin A (ConA). Unlike other plant lectins, both DGL and ConA bind with high affinity to the core trimannoside moiety, 3,6-di-O-(a-~-mannopyranosyl)-a-~-mannopyranoside, which is present in all asparagine-linked carbohydrates. In the present study, hemagglutination inhibition techniques have been used to investigate binding of DGL and ConA to a series of mono-and dideoxy analogs of methyl 3,6-di-0-(a-D-mannopyranosy1)-a-D-mannopyranoside and to a series of asparagine-linked oligomannose and complex oligosaccharides and glycopeptides. The results indicate that both DGL and ConA recognize epitopes on all three residues of the trimannoside: the 3-, 4-, and 6-hydroxyl groups of the a(1-6)Man residue, the 3-hydroxyl group of the a(1-3)Man residue, and the 2-and 4-hydroxyl groups of the central Man residue of the core trimannoside. However, unlike ConA, DGL does not bind to biantennary complex carbohydrates. This was confirmed by showing that biantennary complex glycopeptides do not bind to a DGL-Sepharose affinity column. Unlike ConA, DGL does not show enhanced affinity for a large Nlinked oligomannose carbohydrate (Man9 glycopeptide) relative to the trimannoside. Thus, DGL and ConA share similar epitope recognition of the core trimannoside moiety. However, they exhibit differences in their fine specificities for larger N-linked oligomannose and complex carbohydrates.Keywords: lectin; specificity ; cross-linking ; carbohydrate ; glycopeptide.The seed lectin from Dioclea grandifora (DGL) is a M a d Glc-binding protein isolated from the plant found in North East Brazil. The lectin is devoid of covalently linked carbohydrate, and is reported to be a tetramer with a molecular mass of 100 kDa (Moreira et al., 1983). Like other legume lectins, DGL requires Ca2+ and Mn2+ for its binding activity. The lectin possesses a high degree of sequence similarity with the jack bean lectin concanavalin A (ConA), another member of the Dioclea tribe, and differs in only 52 out of 237 residues (Richardson et al., 1984). Six of the seven residues that have been implicated as ligands for Ca2+ and Mn2+ are conserved, and the seven amino acid residues surrounding the shallow saccharide-binding NMRD, nuclear magnetic relaxation dispersion, the magnetic field dependence of nuclear magnetic relaxation rate (longitudinal) of mlvent protons; CHO, Chinese hamster ovary. 1984).

Binding of Multivalent Carbohydrates to Concanavalin A andDioclea grandiflora Lectin

“…The precipitation reactions were inhibited by the presence of Me-␣Man or dissolved upon addition of the monosaccharide. Thus, the multivalent binding activities of the sugars were confirmed, since tetrameric ConA (12) and tetrameric DGL (33) are known to precipitate with multivalent carbohydrates and glycoproteins. ITC measurements, however, require the presence of soluble complexes during the titration experiment (ϳ1-2 h), and thus conditions in which the sugar complexes with ConA and DGL remained soluble were investigated.…”

In vivo lymphocyte activation and apoptosis by lectins of the Diocleinae subtribe

“…These lectins differ in their binding specificities for complex type carbohydrates (Gupta et al 1996, Dam et al 1998. In addition, they show distinct pHdependent dimer-tetramer equilibrium (Grangeiro et al 1997, Calvete et al 1999.…”

Molecular Cloning and Characterization of ConBr, the Lectin of Canavalia Brasiliensis Seeds

“…The many biochemical, biophysical, and structural studies carried out on ConA, both for the native and ConA-saccharide complexes (Reeke and Becker, 1988;Sharon and Lis, 1990;Naismith et al, 1994;Emmerich et al, 1995;Bouckaert et al, 1995;Naismith and Field, 1996;Harrop et al, 1996;Kanellopoulos et al, 1996a, b;Parkin et al, 1996;Hamodrakas et al, 1997;and cited references), make this protein the best characterized plant lectin and an extensively studied representative of its protein family. However, the lectins from Canavalia ensiformis and Dioclea grandijZora display different fine-saccharide-binding specificity for C-glycosides (Weatherman et al, 1996) and complex carbohydrates (Gupta et al, 1996). In addition, studies from our laboratories indicated that lectins isolated from taxonomically closely related legume plants exert distinct biological activities.…”