The complement binding-like domains of the murine homing receptor facilitate lectin activity.

The leukocyte homing receptor (HR), the endothelial leukocyte adhesion molecule, and gmp140/platelet activation-dependent granule membrane protein are members of a family of adhesion molecules, termed the lectin cell adhesion molecules (LEC-CAMS) which are unified by a multi-domain structure containing a lectin motif, an epidermal growth factor-like (egf) motif, and variable numbers of a complement binding-like (CB) motif. Previous data have indicated a predominant role for the lectin motif in cell adhesion directed by the LEC-CAMS, although the egf-like domain of the HR may also play a potential role in cell binding. While the role(s) of the CB domains in the LEC-CAMS is currently not understood, they have been hypothesized to act as rigid spacers or stalks for lectin and perhaps, egf domain presentation. In this paper, we analyze the functional characteristics of murine HR-IgG chimeras containing the lectin, lectin plus egf, and lectin plus egf plus CB domains. The Mel 14 mAb, an adhesion blocking antibody which recognizes a conformational determinant in the N-terminus of the HR lectin domain, shows a significantly decreased affinity for a HR construct which lacks the CB motifs, consistent with the possibility that the CB domains are involved with lectin domain structure. In agreement with this conjecture, HR mutants lacking the CB domains show a profound decrease in lectin-specific interaction with the carbohydrate polyphosphomannan ester, suggesting that the changes in Mel 14 affinity for the lectin domain are reflected in lectin functionality. Various assays investigating the interactions between the HR deletion mutants and the peripheral lymph node high endothelium, including cell blocking, immunohistochemical staining, and radioactively labeled ligand binding, all showed that removal of the CB domains results in a lack of HR adhesive function. These results imply that the CB domains of the HR, and, by analogy, the other members of the LEC-CAM family, may play important structural roles involving induction of lectin domain conformation and resultant functionality

Endogenous mammalian lectin localized extracellularly in lung elastic fibers.

An affinity-purified antibody preparation raised against a beta-galactoside-binding lectin from bovine lung was used to localize a similar lectin in rat lung by immunofluorescence and by electron microscopy after on-grid staining visualized with colloidal gold conjugated second antibody. The endogenous mammalian lectin was found in smooth muscle cells and squamous alveolar epithelial (type I) cells and was concentrated extracellularly in elastic fibers of pulmonary parenchyma and blood vessels. The extracellular localization of this lectin suggests that it, like others, functions by interaction with extracellular glycoconjugates

Localization of an endogenous lectin in chicken liver, intestine, and pancreas.

Extracts of adult chicken liver, pancreas, and intestine contain high levels of a lectin which appears to be identical to one previously purified from embryonic chick muscle. This lectin is virtually absent from adult muscle, but is highly concentrated in cells lining liver sinusoids, intestinal goblet cells, and the extracellular spaces surrounding pancreatic acini. These findings suggest that the lectin may play different roles in different tissues and at different times in the life of a chicken

The serlogical specificity of the lectin from Lens culinaris

Lens culinaris, the common lentil, contains a lectin which has been shown to be specific for a glycoprotein saliva antigen and a glycolipoprotein serum antigen. Both the saliva and serum precipitin reactions with the lectin are directly inhibited with saccharides, especially those related to D-mannose. Electrophoresis of the serum antigen showed that it migrates as three bands, while appearing as a single band in double diffusion precipitin patterns. Quantitative studies of the saliva antigen levels by hemagglutination inhibition titration indicated a polygenic, quantitative mode of inheritance with a minimum heritability of O. 34. Blood group ABH secretor individuals were found to have a significantly lower mean saliva antigen level than nonsecretor individuals. The lectins from Pisum sativum and Canavaliafiensiformis formed precipitin bands of identity with L.culinaris lectin against saliva. C. ensiformis and L. culinaris lectins exhibited precipitin bands of partial identity against serum; and P. sativum and L. culinaris lectins exhibited a pattern of identity against serum. In addition, precipitin patterns of partial identity with the non-H lectin from Lotus tetragonolobus has been demonstrated. Using Ulex europaeus lectin in hemagglutination inhibition experiments with saliva from blood group O secretor individuals, a minimum heritability of approximately 0.40 for H antigen levels was found. A higher frequency of nonsecretor individuals was observed in the Black population compared with the White population

FGB1 and WSC3 are in planta-induced beta-glucan-binding fungal lectins with different functions

In the root endophyte Serendipita indica, several lectin-like members of the expanded multigene family of WSC proteins are transcriptionally induced in planta and are potentially involved in beta-glucan remodeling at the fungal cell wall. Using biochemical and cytological approaches we show that one of these lectins, SiWSC3 with three WSC domains, is an integral fungal cell wall component that binds to long-chain beta 1-3-glucan but has no affinity for shorter beta 1-3- or beta 1-6-linked glucose oligomers. Comparative analysis with the previously identified beta-glucan-binding lectin SiFGB1 demonstrated that whereas SiWSC3 does not require beta 1-6-linked glucose for efficient binding to branched beta 1-3-glucan, SiFGB1 does. In contrast to SiFGB1, the multivalent SiWSC3 lectin can efficiently agglutinate fungal cells and is additionally induced during fungus-fungus confrontation, suggesting different functions for these two beta-glucan-binding lectins. Our results highlight the importance of the beta-glucan cell wall component in plant-fungus interactions and the potential of beta-glucan-binding lectins as specific detection tools for fungi in vivo

Purification and properties of a plant Agglutinin

Thesis (M.A.)--Boston UniversityThis study involved work with extracts of the seeds of Bauhinia purpurea alba, in which an N specific lectin was found by Mäkelä (37) and Boyd and McMaster (16). There were two main purposes in mind. First, to see if the lectin could be of practical use as a typing sera; and secondly, to get some insight into its chemical make-up. After working out a purification method and a method for checking the agglutinating power of the lectin, the lectin was tested against several small samples. The writer then tested this lectin against 90 random blood samples. The lectin disagreed with rabbit anti-N in one case -- the lectin typed one MN as an M. There is as yet no known reason for this difference, so it would seem that one could not use the lectin as a typing sera at the present time. The lectin was treated with formaldehyde and lost all its activity as a result. Erythrocytes were treated with an enzyme, ficin, and were then reacted with the lectin. The results showed an increase in the titer of the lectin, and the specificity of the lectin was lost. The freezing of a sample of the lectin for four months resulted in the loss of some of its activity. It remained specific, however. Upon dialyzing the crude extract against saline or water, the substances (Y) that remained behind in the membrane became nonspecific. This showed that there were at least two parts to the extract, one of large molecular weight because it would not pass through the membrane, and the other smaller in size because it would pass through the membrane. The substance that passed through the membrane was called X. By dialyzing the crude extract against distilled water and lyophilizing the distilled water, a substance was found which gave the reaction of a sugar and also seemed to have either or both glucosamine and galactosamine present. Since X showed the presence of reducing sugars and could be shown to inhibit Y against the M site on erythrocytes (see Table 7), it was thought that some sugars should be tested against Y to see if any of them would be able to inhibit Y. The same sugars were also tested against the lectin (Table 5). It was found that none of the sugars had any effect on the lectin; but raffinose, melibiose, and galactose all were found to inhibit Y (Table 8). It has also been shown by other workers (13) that lactose will inhibit Y. The inhibition of the sugars against lectin and Y were run in three ways. The first was the usual inhibition method where the inhibiting substance (sugar, in this case) is placed with the substance to be inhibited (Y) and incubated for one hour. Then the appropriate erythrocyte was added. The second method was to place erythrocytes, Y, and sugar all in the same tube at the same time. The third was to incubate sugar and erythrocytes together and then add Y. The results are given in Table 9. It was found by the writer that Method 2 was the best. This agrees with Krüpe as cited in Mäkelä (37) who states that if an appropriate sugar is added to erythrocytes that are agglutinated by a lectin, the lectin will leave the erythrocytes and pick up the sugar. This is shown by the breaking up of the clumps of erythrocytes. The sugars that would inhibit Y were tried against adsorbed rabbit sera, both anti-M and N. The sugars showed no effect against the rabbit sera. The writer feels that the lectin may not be as specific as the rabbit sera; thus, these inhibiting sugars may only be closely related to the true configuration of the M site

Detection of inflammation- and neoplasia-associated alterations in human large intestine using plant/invertebrate lectins, galectin-1 and neoglycoproteins

Commonly, plant and invertebrate lectins are accepted glycohistochemical tools for the analysis of normal and altered structures of glycans in histology and pathology. Mammalian lectins and neoglycoproteins are recent additions to this panel for the detection of lectin-reactive carbohydrate epitopes and glycoligand-binding sites. The binding profiles of these three types of probes were comparatively analyzed in normal, inflamed and neoplastic large intestine. In normal colonic mucosa the intracellular distribution of glycoconjugates and carbohydrate ligand-binding sites in enterocytes reveals a differential binding of lectins with different specificity and of neoglycoproteins to the Golgi apparatus, the rough and smooth endoplasmic reticulum and the apical cell surface. The accessible glycoligand-binding sites and the lectin-reactive carbohydrate epitopes detected by galectin-1 show the same pattern of intracellular location excluding the apical cell surface. Lectin-reactive carbohydrate epitopes detected by plant lectins of identical monosaccharide specificity as the endogenous lectin {[}Ricinus communis agglutinin-I (RCA-I), Viscum album agglutinin (VAA)], however, clearly differ with respect to their intracellular distribution. Maturation-associated differences and heterogeneity in glycohistochemical properties of epithelial cells and non-epithelial cells (macrophages, dendritic cells, lymphocytes) are found. Dissimilarities in the fine structural Ligand recognition of lectins with nominal specificity to the same monosaccharide have been demonstrated for the galactoside-specific lectins RCA-I, VAA and galectin-1 as well as the N-acetylgalactosamine (GalNAc)-specific lectins Dolichos biflorus agglutinin (DBA), soybean agglutinin (SBA) and Helix pomatia agglutinin in normal mucosa and in acute appendicitis. Acute inflammation of the intestinal mucosa found in acute phlegmonous appendicitis is associated with selective changes of glycosylation of mucin in goblet cells mainly of lower and middle crypt segments resulting in an increase of DBA- and SEA-binding sites in the goblet cell population. Appendicitis causes no detectable alteration of neoglycoprotein binding. In contrast, tumorigenesis of colonic adenoma is characterized by increases in lectin-reactive galactose (Gal; Gal-beta 1,3-GalNAc), fucose and N-acetylglucosamine moieties and by enhanced presentation of respective carbohydrate ligand-binding capacity. This work reveals that endogenous lectins and neoglycoproteins are valuable glycohistochemical tools supplementing the well-known analytic capacities of plant lectins in the fields of gastrointestinal anatomy and gastroenteropathology

Beyond the fuzzy lock-and-key: spontaneous symmetry shifts and glycan/lectin logic gates

Changes in the molecular topology of glycan/lectin interaction may explain observed reaction punctuation driven by experimental gradients in reactant concentration. Adoption of a 'biological renormalization' perspective from statistical physics for the analysis of such phase transitions suggests, in marked contrast to conventional physical systems, a broad spectrum of possible universality class behaviors. This spectrum may, in typical perverse biological manner, be of central scientific interest. Generalization, via formalism abducted from coevolutionary theory, suggests that glycan/lectin molecular switches instantiate logic gates that may be as sophisticated as those characterizing basic neural process, if on a different scale

Paths reunited: initiation of the classical and lectin pathways of complement activation

Understanding the structural organisation and mode of action of the initiating complex of the classical pathway of complement activation (C1) has been a central goal in complement biology since its isolation almost 50 years ago. Nevertheless, knowledge is still incomplete, especially with regard to the interactions between its subcomponents C1q, C1r and C1s that trigger activation upon binding to a microbial target. Recent studies have provided new insights into these interactions, and have revealed unexpected parallels with initiating complexes of the lectin pathway of complement: MBL–MASP and ficolin–MASP. Here, we develop and expand these concepts and delineate their implications towards the key aspects of complement activation via the classical and lectin pathways