Trypanosoma cruzi: studies on the interactions of lectins with glycoconjugates of different zymodemes

Detergent extracts were made of eight strains of Trypanosoma cruzi which were representative of the principal zymodemes. The extracts were subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis and the glycoproteins were reacted with 21 different 125I-labeled lectins and autoradiographed. The staining patterns with particular lectins varied considerably between strains. Concanavalin A stained up to 17 distinct bands in some strains. Other lectins such as peanut lectin only stained two bands in zymodeme 1 strains and none in the other zymodemes. The reaction of N-acetylgalactosamine-specific lectins with some bands indicated the presence of this sugar and this was confirmed by analysis of the extracts. The lectin staining patterns provided an insight into the glycoprotein composition of the bands and should indicate whether combinations of lectins can be used in affinity chromatography systems to purify the glycoproteins.     

Lectin-binding proteins in central-nervous-system myelin. Binding of glycoproteins in purified myelin to immobilized lectins

The capacities of immature and mature rat brain myelin, bovine myelin and human myelin to be agglutinated by soya-bean agglutinin, Ricinus communis agglutinin, wheatgerm agglutinin, and Lotus tetragonolobus agglutinin were examined. The first two lectins, which are specific for galactose and N-acetylgalactosamine, strongly agglutinated immature and mature rat myelin, weakly agglutinated bovine myelin, but did not affect human myelin. The other myelin and lectin combinations resulted in very weak or no agglutination. [(3)H]Fucose-labelled glycoproteins of purified adult rat brain myelin were solubilized with sodium dodecyl sulphate and allowed to bind to concanavalin A-Sepharose and each of the other lectins mentioned above, which had been immobilized on agarose. About 60% of the radioactive fucose was in glycoproteins that bound to concanavalin A-Sepharose and these glycoproteins could be eluted with solutions containing methyl alpha-d-mannoside and sodium dodecyl sulphate. Periodate/Schiff staining or radioactive counting of analytical gels showed that most of the major myelin-associated glycoprotein (apparent mol.wt. approx. 100000) bound to the concanavalin A, whereas the glycoproteins that did not bind were mostly of lower molecular weight. Preparative polyacrylamide-gel electrophoresis of the glycoprotein fraction that was eluted with methyl alpha-d-mannoside yielded a relatively pure preparation of the myelin-associated glycoprotein. Similar results were obtained with each of the other lectins, i.e. the myelin-associated glycoprotein was in the fraction that bound to the immobilized lectin. Double-labelling experiments utilizing [(3)H]fucose-labelled glycoproteins from adult myelin and [(14)C]fucose-labelled glycoproteins from 14-day-old rat brain myelin did not reveal any difference in the binding of the mature and immature glycoproteins to any of the immobilized lectins. The results in this and the preceding paper [McIntyre, Quarles & Brady (1979) Biochem. J.183, 205-212] suggest that the myelin-associated glycoprotein is one of the principal receptors for concanavalin A and other lectins in myelin, and that this property can be utilized for the purification of this glycoprotein.     

Structural characterization of glycoprotein carbohydrate chains by using diagoxigenin-labeled lectins on blots

The carbohydrate structures of blotted glycoproteins can be analyzed by probing them with lectins. Here we describe a method where lectins conjugated with digoxigenin are used in combination with an anti-digoxigenin antibody AP conjugate as a very sensitive detection system for this type of analysis. The specificity of the lectins used, and the sensitivity of the detection system, provide valuable conclusions on the glycan structures. Only small amounts of glycoproteins are required for the analysis. The binding specificity of a set of lectins is demonstrated with various glycoproteins of defined carbohydrate structure. The application of these labeled lectins in combination with specific glycosidases for the characterization of the carbohydrate chains of recombinant tissue plasminogen activator and erythropoietin is presented.     

Lectin localization in human nerve by biochemically defined lectin-binding glycoproteins, neoglycoprotein and lectin-specific antibody

Molecular recognition can be mediated by protein (lectin)-carbohydrate interaction, explaining the interest in this topic. Plant lectins and, more recently, chemically glycosylated neoglycoproteins principally allow to map the occurrence of components of this putative recognition system. Labelled endogenous lectins and the lectin-binding ligands can add to the panel of glycohistochemical tools. They may be helpful to derive physiologically valid conclusions in this field for mammalian tissues. Consequently, experiments were prompted to employ the abundant beta-galactoside-specific lectin of human nerves in affinity chromatography and in histochemistry to purify and to localize its specific glycoprotein ligands. In comparison to the beta-galactoside-specific plant lectins from Ricinus communis and Erythrina cristagalli, notable similarities were especially detectable in the respective profiles of the mammalian and the Erythrina lectin. They appear to account for rather indistinguishable staining patterns in fixed tissue sections. Inhibitory controls within affinity chromatography, within solid-phase assays for each fraction of lectin-binding glycoproteins and within histochemistry as well as the demonstration of crossreactivity of the three fractions of lectin-binding glycoproteins with the biotinylated Erythrina lectin in blotting ascertained the specificity of the lectin-glycoprotein interaction. In addition to monitoring the accessible cellular ligand part by the endogenous lectin as probe, the comparison of immunohistochemical and glycohistochemical detection of the lectin in serial sections proved these methods for receptor analysis to be rather equally effective. The observation that the biotinylated lectin-binding glycoproteins are also appropriate ligands in glycohistochemical analysis warrants emphasis.(ABSTRACT TRUNCATED AT 250 WORDS)     

Lectin binding sites of glycoproteins as revealed by lectin-gold-silver and lectin-peroxidase-diaminobenzidine methods

Summary For the precise histochemical detection of lectin binding sites of glycoproteins, the results obtained by lectin-gold-silver (LT-G-S) staining methods have been systematicaly compared with those revealed by alternative techniques of lectin-peroxidase-diaminobenzidine (LT-PO-DAB) reactions in a series of organs from different mammalian species.Ricinus communis agglutinin-I and concanavalin A were the lectins used in the present study. In the tissues subjected to the LT-G-S procedures, reactive tissue structures exhibited positive reactions of varying intensities of black. The results of control staining for the LT-G-S methods substantiated the view that the reaction products demonstrated the precise lectin binding sites of glycoproteins. The staining images obtained by the LT-PO-DAB techniques were not necessarily correlated precisely with those revealed by the LT-G-S procedures, and unavoidable background staining in pale brownish shades was noted in the majority of LT-G-S negative tissue structures. In view of these results, the LT-G-S staining methods employed in the present study are believed to be a reliable technique for the precise localization of saccharide residues of glycoproteins in light microscopy.     

Staining of glycoproteins in polyacrylamide and agarose gels with fluorescent lectins.

We describe a simple and sensitive method for staining of the carbohydrate moiety of glycoproteins in polyacrylamide or agarose electrophoretic gels. Gels are incubated in a solution of fluorescein-labeled concanavalin A. Following destaining with a neutral buffer, glycoproteins exhibit fluorescence under long-range ultraviolet light. Thus, the glucose/mannose containing β- and γ-chains of human fibrinogen give fluorescent bands, whereas the carbohydrate-free α-chain does not react. Less than 100 ng of hexose bound to fibrinogen β- or γ-chains could be detected. The procedure is suitable for staining of other carbohydrate residues in glycoproteins, which can be recognised by specific agglutinins, as shown by binding of fluorescein-labeled lectins from Ricinus communis to galactose residues of fibrinogen.     

LAMP-1 in CHO cells is a primary carrier of poly-N-acetyllactosamine chains and is bound preferentially by a mammalian S-type lectin

Recent studies indicate that some mammalian S-type lectins bind preferentially to oligosaccharides containing the repeating disaccharide [3Gal beta 1,4GlcNAc beta 1]n or poly-N-acetyllactosamine (PL) sequence. We report here our investigation on the distribution of these sequences in glycoproteins in Chinese hamster ovary (CHO) cells and the interaction of glycoproteins containing PL chains with an immobilized S-type lectin (L14) from calf heart tissue. Our results demonstrate that PL chains are carried by a few high molecular weight glycoproteins which are bound by tomato-lectin Sepharose and one of these was precipitated by antibody to LAMP-1 (a lysosomal-associated membrane glycoprotein). More importantly, these high molecular weight glycoproteins, including LAMP-1, were bound with high affinity by L14. These results indicate that mammalian S-type lectins are highly specific in their interactions with glycoproteins and that LAMPs carry important recognition sequences for these lectins.     

Lectin localization in human nerve by biochemically defined lectin-binding glycoproteins,neoglycoprotein and lectin-specific antibody

Summary Molecular recognition can be mediated by protein (lectin)-carbohydrate interaction, explaining the interest in this topic. Plant lectins and, more recently, chemically glycosylated neoglycoproteins principally allow to map the occurrence of components of this putative recognition system. Labelled endogenous lectins and the lectin-binding ligands can add to the panel of glycohistochemical tools. They may be helpful to derive physicologically valid conclusions in this field for mammalian tissues. Consequently, experiments were prompted to employ the abundant -galactoside-specific lectin of human nerves in affinity chromatography and in histochemistry to purify and to localize its specific glycoprotein ligands. In comparison to the -galactoside-specific plant lectins fromRicinus communis andErythrina cristagalli, notable similarities were especially detectable in the respective profiles of the mammalian and the Erythrina lectin. They appear to account for rather indistinguishable staining patterns in fixed tissue sections. Inhibitory controls within affinity chromatography, within solid-phase assays for each fraction of lectin-binding glycoproteins and within histochemistry as well as the demonstration of crossreactivity of the three fractions of lectin-binding glycoproteins with the biotinylated Erythrina lectin in blotting ascertained the specificity of the lectin-glycoprotein interaction. In addition to monitoring the accessible cellular ligand part by the endogenous lectin as probe, the comparison of immunohistochemical and glycohistochemical detection of the lectin in serial sections proved these methods for receptor analysis to be rather equally effective. The observation that the biotinylated lectin-binding glycoproteins are also appropriate ligands in glycohistochemical analysis warrants emphasis. Overall, the introduction of biotinylated mammalian lectins as well as the lectin-binding glycoproteins will aid to critically evaluate the physiological significance of the glycobiological interplay between endogenous lectins and distinct carbohydrate parts of cellular glycoconjugates.     

Identification of glycoproteins on nitrocellulose membranes and gels

In this article we describe a procedure for the detection of glycoproteins on gels employing the periodic acid-Schiff’s reagent. In addition, a number of staining protocols and direct binding ELISA, employing antibodies and lectins, are described for the identification and quantitation of glycoproteins after their immobilization by dot, slot, or Western blotting onto nitrocellulose membranes. We document, in detail, the conditions (i.e., the effect of solvent and detergents) for the immobilization of one specific family of O-linked glycoproteins, namely mucins. However, taking into account our suggestions, these procedures should be applicable to other types of glycoprotein.     

Isolation and characterization of the CNBr peptides from the proteolytically derived N-terminal fragment of ovine opsin.

A panel of lectins was used to analyse glycoproteins of normal granulocytes and leukaemic myeloid cells. The glycoproteins of detergent-solubilized whole cells were separated by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis and their lectin-binding properties determined by incubation of the fixed gels with radioiodinated lectins. Normal granulocytes and leukaemic myeloid cells in different stages of maturation possess a cell-surface sialic acid-rich glycoprotein of apparent mol.wt. 115 000 (GP115), that can be labelled by both the lactoperoxidase and periodate/NaB3H4 cell-surface labelling techniques. The sialoglycoprotein of leukaemic myeloblasts has a slightly lower apparent mol.wt., 112000 (GP112). After neuraminidase treatment before cell solubilization, both GP115 and GP112 bind the lectins from Arachis hypogaea (peanut) and Helix pomatia (snail) and have an increased apparent molecular weight of 125000. Two concanavalin A-binding glycoproteins of apparent mol.wts. 98000 and 90000 are present in leukaemic myeloblasts. Concanavalin A binding to these glycoproteins is decreased in more mature leukaemic cells and absent in granulocytes. As concanavalin A binding decreases in the maturer forms, there is a concomitant increase in the binding of Ricinus communis (castor bean) and Maclura aurantiaca (osage orange) lectins to these glycoproteins. Whole granulocytes, but not leukaemic myeloblasts, contain a major cell-surface concanavalin A binding glycoprotein of apparent mol.wt. 130000, which is labelled by the periodate/NaB3H4 technique. Concanavalin A binding to this glycoprotein increases as the morphology of leukaemic cells approaches that of mature granulocytes.     

Lectin histochemical examination of rabbit bladder glycoproteins and characterization of a mucin isolated from the bladder mucosa

The glycocalyx of the mucosal surface of urinary bladder acts as an effective barrier against invasion by pathogenic microorganisms and injury from toxic substances in the urine. Defects in these bladder mucosal components could thus be important factors in the development of diseases such as interstitial cystitis and lower urinary tract infections. However, information on the nature of glycoconjugates of mammalian bladder mucosa is very limited. In this study, the glycoconjugates of rabbit bladder were examined histochemically using biotinylated lectins with specificities for a variety of carbohydrate moieties. Three [Artocarpus integrifolia (Jacalin), Datura stramonium (DSL), and Maackia amurensis II (MAL-II)] of the lectins bound predominantly to the luminal cell layer, with decreased binding to the basal layers of the epithelium. In contrast, Ricinus communis I and Sambucus nigra lectins did not bind to the cells in the epithelium but strongly interacted with the subepithelial layers, especially the lamina propria. The intensity of the staining by Jacalin and MAL-II was significantly reduced by prior treatment of the bladder sections with O-sialoglycoprotein endopeptidase, indicating that the ligands of these lectins are primarily mucin glycoproteins. In parallel biochemical studies, a high-molecular-weight glycoprotein with characteristics typical of epithelial mucins was purified from the mucosa of rabbit bladder explant cultures metabolically labeled with [(3)H]glucosamine. Quantitative analysis of the sialic acid, uronic acid, and hexosamine contents of delipidated rabbit bladder mucosa revealed a larger proportion of sialoglycoproteins compared with glycosaminoglycans. Taken together, the results of histochemical and biochemical analyses indicate that glycoproteins rather than glycosaminoglycans are the major components of the bladder epithelium, and that the former include a mucin.     

Heterogeneity of cell population of lymphoma NK/Ly and leukemia L-1210 according to carbohydrate structure of cell surface: immunocytochemical analysis of lectin binding

The heterogeneity of tumor cell populations according to binding of lectins from lentil (LcL), wheat germs (WGA), peanut (PNA) and concanavalin A was investigated on a model of murine Nemeth-Kellner lymphoma (NK/Ly) and leukemia L-1210. Bound lectins were detected by indirect immunochemical method using home obtained polyclonal antilectin antibodies and immunogold silver staining (IGSS) technique. Significant differences in binding of Con A were revealed between NK/Ly (67% Con A+) and L-1210 (7.2% Con A+) cells, while the differences in binding of other lectins with both types of tumor cells were not significant. A relatively high percentage of PNA+ cells was registered that can indicate a high degree of desialization of membrane glycoproteins.     

Screening for and purification of novel self-aggregatable lectins reveal a new functional lectin group in the bark of leguminous trees

A solubility-insolubility transition assay was used to screen the bark and stems of seven leguminous trees and plants for self-aggregatable lectins. Novel lectins were found in two trees, Robinia pseudoacacia and Wisteria floribunda, but not in the leguminous plants. The Robinia lectin was isolated from coexisting lectin by combined affinity chromatographies on various sugar adsorbents. The purified lectins proved to be differently glycosylated glycoproteins. One lectin exhibited the remarkable characteristics of self-aggregatable lectins: localization in the bark of legume trees, self-aggregation dissociated by N-acetylglucosamine/mannose, and coexistence with N-acetylgalactosamine/galactose-specific lectins, which are potential endogenous receptors. Self-aggregatable lectins are a functional lectin group that can link enhanced photosynthesis to dissociation of glycoproteins.     

A simple and reliable method for the detection of sialylation in complex/hybrid-type carbohydrate chains of glycoproteins by mixed lectins

A practical and convenient method for discriminating between the presence and the absence of sialic acid in carbohydrate chains of glycoproteins was devised using paramagnetic beads and two lectins, Sambucus sieboldiana lectin (SSA) and Ricinus communis agglutinin (RCA120). The glycoproteins of transferrin or thyroglobulin were firstly captured to paramagnetic beads that were previously coated with corresponding antibody, and then the lectins of RCA120-biotin and SSA-FITC were bound to the glycoproteins on the paramagnetic beads. Finally, the fluorescence intensity of the beads was measured to determine the ratios of lectins RCA120-biotin/Cy5-streptavidin to SSA-FITC. The mixed lectins method showed bigger difference of the ratios between the presence and the absence of sialic acid, indicating higher discrimination efficiency than the ordinary non-mixed lectins method. Furthermore, statistical analysis by two-side t-test indicated that the mixed lectins method was more highly reliable than the ordinary non-mixed lectins method in discriminating between the presence and the absence of sialic acid. The reaction with the two lectins can be performed in a single tube and readily automated taking advantage of the use of paramagnetic beads.     

Carbohydrate and glycoprotein specificity of two endogenous cerebellar lectins

Two endogenous cerebellar mannose binding lectins have been isolated in an active form by immunoaffinity chromatography employing their respective immobilized antibodies. One of them, termed cerebellar soluble lectin (CSL), was extracted in the absence of detergents, whereas the other, called Receptor 1 (R1), was soluble only in the presence of detergents. Tests of inhibition of agglutination of erythrocytes were performed with mono-, oligo and polysaccharides, as well as glycoconjugates of known structures. On the basis of agglutinating activities these 2 lectins are different from the previously reported lectins in brain, since they were not inhibited by galactosides and lactosides and were only marginally inhibited by glycosaminoglycans. CSL and R1 were better inhibited by mannose-rich glycopeptides as compared to the corresponding oligosaccharides. The different inhibition patterns obtained with glycans of known structures indicated that these lectins are very discriminative. Although CSL and R1 have similar specificities, they differed in their binding properties towards glycopeptides of ovalbumin. Both lectins showed considerable affinity for endogenous cerebellar glycopeptides, also rich in mannose. These glycopeptides belong to a few endogenous Con A-binding cerebellar glycoprotein subunits and are not present on other endogenous Con A-binding glycoproteins. In the forebrain, where CSL and R1 were also present, at least some of the glycoproteins interacting with the lectins were different from that observed in the cerebellum. Our data overall suggest that specific cell recognition in the nervous system could be invoked via the interactions between widely distributed lectins and cell-specific glycoproteins.     

FRACTIONATION OF GLYCOPROTEINS ASSOCIATED TO ADULT RAT BRAIN MYELIN FRACTIONS

Abstract— The chloroform-methanol insoluble residue of adult rat brain myelin fractions (My-CMI) contains only 20% of protein but all myelin-associated glycoproteins (Z anetta et al ., 1977a). After solubilization in sodium dodecyl sulphate, these glycoproteins were separated by sequential affinity chromatography on 4 immobilized lectins. Ten fractions (9 of which contained only glycoproteins) were obtained. Glycoproteins added up to at least 25% of My-CMI proteins. Many minor glycoproteins were detected in the different fractions. However most of them appeared not to be intrinsic to myelin. On the contrary a major glycoprotein electrophoretic band, component A, appeared to be intrinsic to myelin although its presence also on oligodendrocyte plasma membrane cannot be excluded. Component A was tentatively identified with the'major myelin associated glycoprotein'described by QUARLES (1972, 1973 a, b ). It accounted for less than 0.4% of proteins and 8% of glycoproteins of myelin fractions and consisted of at least two'glycopolypeptides'which, both, bind to concanavalin A and to the Ulex europeus lectin. The other major glycoprotein, component B, did not bind to any of the lectins used and, thus, must have N -acetyl neuraminic acid as only terminal sugar. The separation of myelin-associated glycoproteins according to their affinity for lectins allowed a tentative identification of the lectin binding sites of myelin sheath.     

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.     

Comparison of lectin receptor and membrane coat-associated glycoproteins of milk lipid globule membranes.

1. Glycoproteins of bovine (Bos taurus) and human (Homo sapiens) milk lipid globule membranes were characterized by ability to bind lectins after electrophoretic separation. 2. Seven lectin receptor glycoproteins were detected in bovine and five in human milk lipid globule membranes. Bovine and human globule membrane glycoproteins differed in ability to interact with certain lectins. 3. Two major nonionic detergent insoluble glycoproteins were present in bovine and human lipid globule membrane; these constituents had apparent molecular weights of 155,000 and 69,000. Detergent-insoluble polypeptides with similar or identical electrophoretic mobilities were found in milk lipid globule membranes from four other species, rat (Rattus norvegicus), sheep (Ovis aries), pig (Sus scrofa) and goat (Capra hircus). Tryptic peptide mapping revealed these polypeptides to be nonidentical among species.     

Preventing Ralstonia solanacearum adhesion with glycans from cashew, cocoa, coffee, pumpkin, and tomato seed extract

Ralstonia solanacearum wilts many plants, causing heavy agricultural losses. Its pathogenic strain ATCC 11696 produces 2 hemagglutinating lectins: RSL and RS-IIL. These lectins may bind to terminal l-fucose-, d-arabinose-, and d-mannose-bearing seedling xylem cell wall glycans, thus enabling pathogen adhesion to them, with devastating infection establishment. Blocking the active sites of these lectins with seed embryo-surrounding oligo- and poly-saccharides hampers binding of the lectins to the embryos. The current study shows that seeds of cashew, cocoa, coffee, pumpkin, and tomato contain low and high molecular mass glycans that block RSL and RS-IIL (like its homologous Pseudomonas aeruginosa PA-IIL lectin). The blocking of the pathogen lectins, which is attributable to the documented composition of the oligo- and poly-saccharides of these seeds, is similar to that observed with animal glycoproteins of avian egg whites (protecting their embryos from infections) and of milk and royal jelly, which likewise protect mammal and bee neonates, respectively. RSL was most strongly inhibited by cashew seed glycans, and RS-IIL by coffee seed glycans. Western blot analyses with these lectins instead of antibodies revealed the hitherto undescribed presence of lectin-binding glycoproteins in the coffee, pumpkin, tomato, and cashew (but not cocoa) seeds. The use of these lectins for unveiling potent embryo-protecting seed glycans might be helpful for seedling-bioprotection projects similar to those planned for animal protection against antibiotic-resistant infections.     

Seasonally occurring lectins from the bryozoan Bugula neritina

Two different lectins (termed BnA-I and BnA-II) with distinct carbohydrate specificities were identified and subsequently isolated from the marine bryozoan Bugula neritina. BnA-I hemagglutinating activity was inhibited by N-acetylated hexosamines, their polymers, and glycoproteins rich in these moieties. BnA-II-induced hemagglutination was not blocked by any simple sugars but could be inhibited by several complex glycoproteins (e.g., thyroglobulin and orosomucoid). Both lectins required the presence of Ca(+)+ for reactivity and were purified by affinity chromatographic procedures. Purified BnA-I was determined to have a native molecular weight of 240 Kd and appeared to be a hexameric homopolymer while BnA-II was shown to be a 65-70 Kd monomer. Both lectins showed seasonality in expression, BnA-I appearing in animal extracts prepared in the spring and fall while BnA-II was expressed only during the summer and winter.