Lectin-induced modulation of the antibody response to type III pneumococcal polysaccharide

Several lectins were tested for their capacity to alter the antibody response to type III pneumococcal polysaccharide (SSS-III). The antibody response was enhanced by concanavalin A (Con A), phytohemagglutinin (PHA), as well as lectins from Phytolacca americana (Pa-2), Pisum sativum (PSA), and Lens culinaris (LCH), when these lectins were given 2 days after immunization with SSS-III; however, suppression was obtained when Con A and Pa-2 were given at the time of immunization. By contrast the lectins from Vicia villosa (VVL) and Bauhinia purpurea (BPA) did not alter the antibody response. Since the lectins PSA and LCH bind to the same monosaccharide as Con A, whereas the other lectins bind to different monosaccharides, these findings indicate that there is no relationship between nominal monosaccharide specificity and the capacity to modulate the antibody response. Substantial increases in the magnitude of the IgG₁ antibody response was noted after the administration of Con A whereas profound enhancement of IgG_2a antibody response was noted after PHA was given.     

Preparation and properties of metal ion derivatives of the lentil and pea lectins

Lentil lectin (LcH) and pea lectin (PSA) belong to the class of D-glucose/D-mannose binding lectins and resemble concanavalin A (Con A) closely in physicochemical, structural, and biological properties. LcH and PSA, like Con A, are Ca2+-Mn2+ metalloproteins that require the metal ions for their saccharide binding and biological activities. Studies of the relationship between the metal ions binding and saccharide binding activity in LcH and PSA have been difficult due to the problem of metal ion replacement in these proteins. We now report a method of metal ion replacement in both lectins that allows substitution of the Mn2+ in the native proteins with a variety of transition metal ions, as well as substitution of the Ca2+ with Cd2+ in a particular complex. The following metal ion derivatives of both LcH and PSA have been prepared: Ca2+-Zn2+, Ca2+-Co2+, Ca2+-Ni2+, and Cd2+-Cd2+. All of these derivatives are as active as the native lectins, as demonstrated by precipitation with specific polysaccharides, saccharide inhibition of precipitation, and hemagglutination assays. The yields of these derivatives are good (generally greater than 70%), and the degree of metal ion incorporation is high (generally greater than 90%). The method of preparation is quite different from that for metal ion substitution in Con A, which proceeds via the apoprotein. In contrast, the apoproteins of LcH and PSA are unstable, aggregate above pH 4.0, and cannot be remetallized once formed.(ABSTRACT TRUNCATED AT 250 WORDS)     

Selective interactions of lectins with amino acid taste receptor sites in the channel catfish

Five lectins of varying carbohydrate specificities, Dolichosbiflorus (DBA), jacalin, Phaseolus vulgaris (PHA), Pisum sativum(PSA) and Ricinus communis (RCA I), were used to extend characterizationof the glycoprotein nature of taste plasma membranes and todifferentially affect the binding of two taste stimuli, L-alanineand L-arginine, to their respective taste receptor sites inthe cutaneous taste system of the channel catfish (Ictaluruspunctatus). The binding of the taste stimulus L-arginine toa partial membrane fraction (P_–) from taste epitheliumwas inhibited by 68 and 74% by preincubation in the presenceof the unconjugated lectins PHA and RCA I respectively. A correspondinglevel of inhibition of L-alanine binding was seen in the presenceof RCA I (76%); however, PHA had little effect upon L-alaninebinding. DBA appeared to selectively inhibit L-alanine but notL-arginine binding (60 versus 8% respectively) while jacalinmoderately inhibited the binding of both stimuli to fractionP2. PSA had little effect upon the binding of either L-alanineor L-arginine (4 and 5% inhibition respectively). Inhibitionof taste receptor binding by all lectins was time- and dose-dependent,and was fully abolished by incubation in the presence of theappropriate hapten sugar. The biotinylated lectins DBA, jacalin,PHA, RCA I and concanavalin A (Con A) were used to identifythe glycoprotein components of the chemosensory plasma membranesafter polyacrylamide gel electrophoresis. As previously shown,numerous protein components were labeled by Con A. In contrast,only a few minor protein components were labeled by PHA, DBAand RCA I. This differential labeling of the taste membranesand the differential inhibition of receptor binding by lectinssuggest that they may prove useful as tools in the isolationand purification of taste receptor proteins.     

Lectin binding and inhibition studies reveal the importance of D-glucose, D-mannose and N-acetylglucosamine during early sexual development of Dictyostelium discoideum

Fluorescein-conjugated and non-conjugated lectins were used to determine which surface sugars are involved in the early events of sexual (macrocyst) development in Dictyostelium discoideum. Only zygote giant cells showed unique binding of FITC-WGA and FITC-PNA while all cell types (amoebae, gametes, binucleates, giant cells) showed identical patterns of FITC-Con A, -Gorse and -RCA II binding. In spite of its non-selective labelling of all cell types, Con A inhibited macrocyst formation. The temporal addition of Con A with and without specific hapten sugars indicates the importance of both D-mannose and D-glucose in phagocytosis and, possibly, cell fusion. WGA also inhibited macrocyst formation. Varying the time of addition of the lectin plus/minus its primary hapten sugar implicates N-acetylglucosamine as being important in cell fusion. Neither Gorse, RCA II nor PNA had any detectable inhibitory effects on macrocyst development leaving the appearance of increased PNA receptors at the giant cell surface as an enigma.     

Binding of N-acetylgalactosamine-specific lectins to spin-labeled galactosamine derivatives

Legume seed lectins specific for N-acetyl-alpha-D-galactosaminyl end groups from Amphicarpaea bracteata, lima bean, Griffonia simplicifolia, Dolichos biflorus, and soybean were compared with respect to binding of several spin-labeled derivatives of D-galactosamine by electron spin resonance and precipitin inhibition analysis. Spin-label II [methyl 2-[[(2,2,5,5-tetramethyl-1-oxopyrrolidin-3-yl) carbonyl]amino]-2-deoxy-alpha-D-galactopyranoside], spin-label III [1-(methyl 2-deoxy-alpha-D-galactopyranosid-2-yl)-3-(2,2,6, 6-tetramethyl-1-oxypiperidin-4-yl)-2-thiourea], and spin-label IV [1-[4-[[(methyl 2-deoxy-alpha-D-galactopyranosid-2-yl)amino]carbonyl]phenyl]-3-(2, 2,6-tetramethyl-1-oxypiperidin-4-yl)-2-thiourea] contain 2-N-(oxypiperidinyl) or 2-N-(oxypyrrolidinyl) substituents varying in length and polarity of the linker arm between the glycoside and nitroxide ring. Spin-labels II and III were found to bind very weakly to all the lectins tested (Kd greater than or equal to 1.0 mM). Spin-label IV, containing a planar, nonpolar 2-N-phenyl group, was bound very strongly (Kd = 0.1-0.4 mM) and was moderately immobilized (2T parallel = 48-56 G) by all lectins except that from D. biflorus. Notably, the affinity of spin-label IV to lima bean lectin was 18-fold greater than that for methyl N-acetyl-alpha-galactosaminide. These results suggest that when the bulky oxypiperidinyl moiety lies in a position close to the sugar ring, it interferes with binding; in the cases where a phenyl group spacer exists, the aromatic ring in some cases actually enhances binding.(ABSTRACT TRUNCATED AT 250 WORDS)     

Enhanced glycosylation of a melanoma cell surface glycoprotein by retinoic acid: carbohydrate chain analysis by lectin binding

Retinoic acid (RA) inhibits the growth of mouse S91-C2 melanoma cells and enhances the glycosylation of a cell surface sialoglycoprotein (gp160). The present study analyzed the binding of 125I-labeled lectins to gp160 within polyacrylamide slab gels after electrophoretic separation of cellular macromolecules. Wheat germ agglutinin (WGA) and concanavalin A (Con A) bound to gp160 of RA-treated cells (RA-gp160) more extensively than to gp160 of control cells (C-gp160). Lens culinaris hemagglutinin (LCH), pokeweed mitogen (PWM), Ricinus communis agglutinin I (RCAI), and peanut agglutinin (PNA) failed to bind to either C-gp160 or to RA-gp160. The binding of WGA was greatly diminished after sialic acid removal. In contrast, desialylation made possible the binding of RCAI to RA-gp160. LCH, PWM and PNA did not bind to gp160 even after desialylation. Smith degradation exposed WGA-binding sites on RA-gp 160. These results suggest that gp 160 contains one or more highly branched, sialylated, N-linked complex-type side chains and lacks O-linked oligosaccharides and poly N-acetyllactosamine side chains.     

Dairy bacteria remove in vitro dietary lectins with toxic effects on colonic cells

Aims:  To assess in vitro the ability of some dairy bacteria to bind concanavalin A (Con A), peanut agglutinin (PNA) and jacalin (AIL), preventing their toxicity on mouse intestinal epithelial cells (IEC).
Methods and Results:  Con A and AIL reduced significantly IEC viability in vitro , as determined by Trypan Blue dye exclusion or by propidium iodide/fluorescein diacetate/Hoescht staining. Different strains of dairy bacteria were able to remove lectins from the media. Two strains were subjected to treatments used to remove S-layer, cell wall proteins, polysaccharides and lectin-like adhesins. They were then assayed for the ability to bind dietary lectins and reduce toxicity against IEC and to adhere to IEC after interaction with lectins. Con A and AIL were removed by Propionibacterium acidipropionici and Propionibacterium freudenreichii by binding with specific sugar moieties on the bacterial surface. Removal of lectins by bacteria impaired IEC protection. Adhesion of P. acidipropionici to IEC was reduced but not abolished after binding Con A or AIL.
Conclusions:  Removal of Con A or AIL by dairy propionibacteria was effective to avoid the toxic effect against colonic cells in vitro.
Significance and Impact of the Study:  Consumption of foods containing these bacteria would be a tool to protect the intestinal epithelia.     

Plant Lectins Induce the Production of a Phytoalexin in Pisum sativum

The effects of several plant lectins on the production of apea phytoalexin, pisatin, were examined. Con A, PHA, PNA andPSA each induced the production of pisatin in pea epicotyl tissues,demonstrating that plant lectins can act as elicitors. The productionof pisatin in response to PHA, PNA or PSA was not affected bythe simultaneous presence of the respective hapten sugars, whereashaptens specific for Con A, such as -D-mannose and methyl--D-mannoside,abolished the induction of pisatin by Con A. These results indicatethat the elicitor effect of Con A is attributable to its abilityto bind to specific carbohydrates in pea cells. Induction ofthe production of pisatin by Con A was markedly inhibited bythe suppressor derived from a pea pathogen, Mycosphaerella pinodes,and by several inhibitors related to signal-transduction pathways.It is suggested, therefore, that the Con A-induced productionof pisatin in pea tissues might be associated with activationof a signal-transduction pathway. An additive effect on theaccumulation of pisatin was observed when Con A was presentwith a polysaccharide elicitor from M. pinodes, suggesting thatexogenous Con A does not compete with the recognition site(s)for the fungal elicitor in pea cells. The present data alsoindicate that Con A may be useful for characterization of thesignal-transduction system that leads to the synthesis of phytoalexinin pea epicotyl tissues. (Received November 16, 1994; Accepted April 20, 1995)     

Trypanosoma rhodesiense Bloodstream Trypomastigote and Culture Procyclic Cell Surface Carbohydrates1, 2, 3

Bloodstream trypomastigote and culture procyclic (insect midgut) forms of a cloned T. rhodesiense variant (WRATat 1) were tested for agglutination with the lectins concanavalin A (Con A), phytohemagglutinin P (PP), soybean agglutinin (SBA), fucose binding protein (FBP), wheat germ agglutinin (WGA), and castor bean lectin (RCA). Fluorescence-microscopic localization of lectin binding to both formalin-fixed trypomastigotes and red cells was determined with fluorescein isothiocyanate (FITC)-conjugated Con A, SBA, FBP, WGA, RCA, PNA (peanut agglutinin), DBA (Dolichos bifloris), and UEA (Ulex europaeus) lectins. Electron microscopic localization of lectin binding sites on bloodstream trypomastigotes was accomplished by the Con A-horseradish peroxidase-diaminobenzidine (HRP-DAB) technique, and by a Con A-biotin/avidin-ferritin method. Trypomastigotes, isolated by centrifugation or filtration through DEAE-cellulose or thawed after cryopreservation, were agglutinated by the lectins Con A and PP with agglutination strength scored as Con A < PP. No agglutination was observed in control preparations or with the lectins WGA, FBA or SBA. Red cells were agglutinated by all the lectins tested. Formalin-fixed bloodstream trypomastigotes bound FITC-Con A and FITC-RCA but not FITC-WGA, -SBA, -PNA, -UEA or -DBA lectins. All FITC-labeled lectins bound to red cells. Con A receptors, visualized by Con A-HRP-DAB and Con A-biotin/avidin-ferritin techniques, were distributed uniformly on T. rhodesiense bloodstream forms. No lectin receptors were visualized on control preparations. Culture procyclics lacked a cell surface coat and were agglutinated by Con A and WGA but not RCA, SBA, PP and FBP. Procyclics were not agglutinated by lectins in the presence of competing sugar at 0.25 M. The expression of lectin binding cell surface saccharides of T. rhodesiense WRATat 1 is related to the parasite stage. Sugars resembling α-D-mannose are on the surface of bloodstream trypomastigotes and culture procyclics; n-acetyl-D-galactosamine and D-galactose residues are on bloodstream forms; and n-acetyl-D-glucosamine-like sugars are on procyclic stages.     

Insight into odorant perception: the crystal structure and binding characteristics of antibody fragments directed against the musk odorant traseolide.

Monoclonal antibodies were elicited against the small hydrophobic hapten traseolide, a commercially available musk fragrance. Antibody variable region sequences were found to belong to different sequence groups, and the binding characteristics of the corresponding antibody fragments were investigated. The antibodies M02/01/01 and M02/05/01 are highly homologous and differ in the binding pocket only at position H93. M02/05/01 (H93 Val) binds the hapten traseolide about 75-fold better than M02/01/01 (H93 Ala). A traseolide analog, missing only one methyl group, does not have the characteristic musk odorant fragrance. The antibody M02/05/01 binds this hapten analog about tenfold less tightly than the original traseolide hapten, and mimics the odorant receptor in this respect, while the antibody M02/01/01 does not distinguish between the analog and traseolide. To elucidate the structural basis for the fine specificity of binding, we determined the crystal structure of the Fab fragment of M02/05/01 complexed with the hapten at 2.6 A resolution. The crystal structure showed that only van der Waals interactions are involved in binding. The somatic Ala H93 Val mutation in M02/05/01 fills up an empty cavity in the binding pocket. This leads to an increase in binding energy and to the ability to discriminate between the hapten traseolide and its derivatives. The structural understanding of odorant specificity in an antibody gives insight in the physical principles on how specificity for such hydrophobic molecules may be achieved.     

Lectin Binding to the Root and Root Hair Tips of the Tropical Legume Macroptilium atropurpureum Urb

Ten fluorescein isothiocyanate-labeled lectins were tested on the roots of the tropical legume Macroptilium atropurpureum Urb. Four of these (concanavalin A, peanut agglutinin, Ricinis communis agglutinin I [RCA-I], wheat germ agglutinin) were found to bind to the exterior of root cap cells, the root cap slime, and the channels between epidermal cells in the root elongation zone. One of these lectins, RCA-I, bound to the root hair tips in the mature and emerging hair zones and also to sites at which root hairs were only just emerging. There was no RCA-I binding to immature trichoblasts. Preincubation of these lectins with their hapten sugars eliminated all types of root cell binding. By using a microinoculation technique, preincubation of the root surface with RCA-I lectin was found to inhibit infection and nodulation by Rhizobium spp. Preincubation of the root surface with the RCA-I hapten beta-d-galactose or a mixture of RCA-I lectin and its hapten failed to inhibit nodulation. Application of RCA-I lectin to the root surface caused no apparent detrimental effects to the root hair cells and did not prevent the growth of root hairs. The lectin did not prevent Rhizobium sp. motility or viability even after 24 h of incubation. It was concluded that the RCA-I lectin-specific sugar beta-d-galactose may be involved in the recognition or early infection stages, or both, in the Rhizobium sp. infection of M. atropurpureum.     

应用生物素标记的凝集素分析登革Ⅱ型病毒糖蛋白

应用十二种生物素标记的凝集素,分析了经SDS-PAGE和电转印分离的登革Ⅱ型病毒(D_2V)糖蛋白。结果表明:D_2V的包膜糖蛋白E可与三种D-甘露糖特异的凝集素(conAPSA及LCA)结合,提示E蛋白的寡糖链为高甘露糖型。D_2V的糖基化非结构蛋白NS_1可与两种D-甘露糖特异的凝集素conA及LCA结合,提示NS_1的寡糖链亦为高甘露糖型。实验结果还显示了一些可能为C6/36细胞感染D_2V后新合成、合成量增加或减少以至完全受抑制的糖蛋白成分,有关这些糖蛋白的性质、功能、意义尚不清楚。在本实验条件下,这种生物素标记凝集素印迹法证明了其敏感性和糖基特异性,可以作为分析各种微量含糖大分子的一种实用方法。     

Purification and properties of blood-group-specific lectins from Vicia cracca.

The lectins from the seeds of Vicia cracca react specifically with human blood group A erythrocytes. They were purified by affinity chromatography on an adsorbent containing matrix-bound N-acyl-D-galactosamine. By a continuous pH gradient the lectins could be separated into two fractions each of which was shown to consist of several agglutinating species. The behaviour of both fractions in affinity chromatography was paralleled by the pH dependence of the interaction with the hapten sugar N-acetyl-D-galactosamine. Both lectin fractions have the same molecular (125000) and subunit (33000) weights, display the same pH dependence of their titre against A1 erythrocytes, and bind to N-acetyl-D-galactosamine at pH 8 with the same constant of about 6 X 10(3)M-1.     

Effect of N-(3-phenyl-2-propenyl)-1-deoxynojirimycin on the lectin binding to HIV-1 glycoproteins

The effect of N-(3-phenyl-2-propenyl)-1-deoxynojirimycin (ppDNM) on the lectin binding to HIV-1 glycoprotein was analyzed by using biotinylated lectins of various sugar specificities as probes. ppDNM potentially inhibited HIV-1-induced syncytium formation and viral infectivity of HIV-1 without cytotoxicity. The lectin binding assay showed that ppDNM treatment reduced Con A binding to gp120 of HIV-1.     

Purification of the glycoprotein lectin from the broad bean (Vicia faba) and a comparison of its properties with lectins of similar specificity.

1. The lectin from the broad bean (Vicia faba) was purified by affinity chromatography by using 3-O-methylglucosamine covalently attached through the amino group to CH-Sepharose (an omega-hexanoic acid derivative of agarose). Its composition and the nature of its subunits were compared with concanavalin A and the lectins from pea and lentil. 2. Unlike the other three lectins, broad-bean lectin is a glycoprotein; a glycopeptide containing glucosamine and mannose was isolated from a proteolytic digest. 3. The mol.wt. is about 47500; the glycoprotein consists of two apprently identical subunits, held together by non-covalent forces. Fragments of the subunits, similar to those found in concanavalin A and soya-bean agglutinin, were found in active preparations. 4. Broad-bean lectin was compared with concanavalin A and the lectins from pea and lentil in an investigation of the inhibition of their action by a number of monosaccharides, methyl ethers of monosaccharides, disaccharides and glycopeptides. The most striking differences concern 3-O-substituted monosaccharides, which are strong inhibitors of the action of broad-bean, pea and lentil lectins but not of the action of concanavalin A. There is, however, no strong inhibition of the action of these lectins by 3-Olinked disaccharides.     

Nuclear magnetic resonance investigation of cadmium 113 substituted pea and lentil lectins

The lentil (LcH) and pea (PSA) lectins, which are members of the class of D-glucose/D-mannose binding lectins, are Ca2+ X Mn2+ metalloproteins that require the metal ions for their saccharide binding and biological activities. We have prepared a variety of Cd2+ derivatives of PSA and LcH, with Cd2+ in either the transition metal (S1) or calcium (S2) sites, or in both. Thus, Cd2+ X Zn2+, Cd2+ X Mn2+, and Ca2+ X Cd2+ derivatives were prepared, in addition to the Cd2+ X Cd2+ derivatives which we have recently reported. This is the first report of stable mixed metal Cd2+ complexes of lectins. The physical and saccharide binding properties of the Cd2+ derivatives of both lectins were characterized by a variety of physiochemical techniques and found to be the same as those of the corresponding native proteins. 113Cd NMR spectra of mono- and disubstituted 113Cd2+ complexes of LcH and PSA were recorded and compared with 113Cd NMR data for concanavalin A (ConA) (Palmer, A.R., Bailey, D.B., Behnke, W.D., Cardin, A.D., Yang, P.P., and Ellis, P.D. (1980) Biochemistry 19, 5063-5070). The data for the PSA and LcH derivatives were found to be very similar, indicating close homology of their metal ion binding sites. 113Cd resonances at 44.6 ppm and -129.4 ppm for 113Cd2+ X 113Cd2+ X LcH, and at 46.6 and -130.4 for the corresponding PSA derivative, are chemical shifts very similar to those observed for 113Cd2+ X 113Cd2+ X ConA. Assignment of the resonances to the transition metal (S1) and calcium (S2) sites were unambiguous since the Ca2+ X 113Cd2+ and 113Cd2+ X Zn2+ derivatives of both lectins showed single resonances characteristic of the S1 and S2 sites, respectively. The results indicate that, unlike ConA, 113Cd2+ binds tightly to PSA and LcH. Binding of monosaccharide to both lectins induce small (2 ppm) upfield shifts in their S2 113Cd resonances, in contrast to the larger shift (8 ppm) observed in ConA. The 113Cd2+ X Mn2+ complexes of PSA and LcH fail to show a 113Cd resonance characteristic of these derivatives, which provides evidence for the close proximity of the metal ions in the two proteins. The present findings indicate that the coordinating ligand atoms to the metal ions at the S1 and S2 sites in LcH, PSA, and ConA are the same.     

Localization of lectins in legume cotyledons.

High-resolution techniques for the localization of lectins are described. Concanavalin A (Con A) and phytohaemagglutinin (PHA) are localized using a fluorescent method with (FITC)-labelled immunoglobulins which bind to the lectins in sections of jack and red kidney bean cotyledons. Specificity is defined by the use of specific sugar inhibitors. Both Con A and PHA are found in cytoplasmic sites. Lectins with beta-glycoside specificity are detected with red-coloured artificial carbohydrate antigens. The beta-galactosyl and beta-glucosyl antigens bind specifically to clusters of spherical bodies in the intercellular spaces, to cell wall sites, and to the periphery of the cytoplasm associated with the cell membrane.     

Isolation of sulfited oligosaccharides from glycoproteins treated with alkaline sulfite

The oligosaccharide products resulting from treatment of mucin-type glycoproteins with alkali in the presence of the sulfite anion have been investigated. Treatment of fetuin and of tryptic glycopeptides from the human erythrocyte with this reagent resulted in the release of sulfited oligosaccharides identified as N-acetylsulfohexosamine (HexNAcSO3), alpha-NeuAc-(2----6)-HexNAcSO3, and alpha-NeuAc-(2----3)-Gal-(1----3 or 4)-[GlcNAc-(1----6)]-HexNAcSO3. In addition, 2.7 moles of sialic acid were released per mole of alpha-NeuAc-(2----6)-HexNAcSO3 from fetuin. The sulfohexosamine moiety is formed via unsaturated intermediates from a 3-O-substituted 2-acetamido-2-deoxy-D-galactosyl residue at the carbohydrate-peptide linkage site when this residue is not substituted at O-4 by another sugar residue. A reaction mechanism accounting for the release of the sulfited oligosaccharides from a 3-O- and 6-O-substituted hexosamine is proposed in which the oligosaccharide branch attached to O-6 is obtained as a specific fragment terminating in sulfohexosamine.     

Crystal structure of fungal lectin: six-bladed beta-propeller fold and novel fucose recognition mode for Aleuria aurantia lectin

Aleuria aurantia lectin is a fungal protein composed of two identical 312-amino acid subunits that specifically recognizes fucosylated glycans. The crystal structure of the lectin complexed with fucose reveals that each monomer consists of a six-bladed beta-propeller fold and of a small antiparallel two-stranded beta-sheet that plays a role in dimerization. Five fucose residues were located in binding pockets between the adjacent propeller blades. Due to repeats in the amino acid sequence, there are strong similarities between the sites. Oxygen atoms O-3, O-4, and O-5 of fucose are involved in hydrogen bonds with side chains of amino acids conserved in all repeats, whereas O-1 and O-2 interact with a large number of water molecules. The nonpolar face of each fucose residue is stacked against the aromatic ring of a Trp or Tyr amino acid, and the methyl group is located in a highly hydrophobic pocket. Depending on the precise binding site geometry, the alpha- or beta-anomer of the fucose ligand is observed bound in the crystal. Surface plasmon resonance experiments conducted on a series of oligosaccharides confirm the broad specificity of the lectin, with a slight preference for alphaFuc1-2Gal disaccharide. This multivalent carbohydrate recognition fold is a new prototype of lectins that is proposed to be involved in the host recognition strategy of several pathogenic organisms including not only the fungi Aspergillus but also the phytopathogenic bacterium Ralstonia solanacearum.     

SOLUBLE AND MEMBRANE LECTIN-BINDING GLYCOPROTEINS OF THE CHROMAFFIN GRANULE

Abstract— Fluorescein isothiocyanate-labelled lectins were used to identify lectin-binding glycoproteins of the chromaffin granule after electrophoresis of the membrane and soluble granule proteins on sodium dodecyl sulphate polyacrylamide slab gels. The glycoprotein nature of all lectin-binding bands was confirmed by staining the gels for carbohydrates, and the specificity of the lectin-binding was demonstrated by hapten sugar inhibition of binding. In samples of granule membrane proteins reduced with dithiothreitol 10 concanavalin A (Con A), 5 wheat germ agglutinin, 8 Ricinus communis agglutinin-60, and 7 Ricinus communis agglutinin-120 (RCA-120) binding glycoproteins were identified. Molecular weights of these glycoproteins varied from 20,000 to 200,000 daltons. All but two of the Con A-binding bands and one of the RCA-120 binding bands appeared to react with more than one lectin, suggesting possible carbohydrate heterogeneity in these membrane glycoproteins. The band identified as dopamine β-hydroxylase reacted most intensely with all four lectin tested, and in the soluble core material this enzyme was the sole significant lectin binding glycoprotein.