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PubMed2004

The X-ray structure of human mannan-binding lectin-associated protein 19 (MAp19) and its interaction site with mannan-binding lectin and L-ficolin.

MAp19 is an alternative splicing product of the MASP-2 gene comprising the N-terminal CUB1-epidermal growth factor (EGF) segment of MASP-2, plus four additional residues at its C-terminal end. Like full-length MASP-2, it forms Ca(2+)-dependent complexes with mannan-binding lectin (MBL) and L-ficolin. The x-ray structure of human MAp19 was solved to a resolution of 2.5 A. It shows a head to tail homodimer held together by interactions between the CUB1 module of one monomer and the EGF module of its counterpart. A Ca(2+) ion bound to each EGF module stabilizes the dimer interfaces. A second Ca(2+) ion is bound to the distal end of each CUB1 module, through six ligands contributed by Glu(52), Asp(60), Asp(105), Ser(107), Asn(108), and a water molecule. Compared with its counterpart in human C1s, the N-terminal end of the MAp19 CUB1 module contains a 7-residue extension that forms additional inter-monomer contacts. To identify the residues involved in the interaction of MAp19 with MBL and L-ficolin, point mutants were generated and their binding ability was determined using surface plasmon resonance spectroscopy. Six mutations at Tyr(59), Asp(60), Glu(83), Asp(105), Tyr(106), and Glu(109) either strongly decreased or abolished interaction with both MBL and L-ficolin. These mutations map a common binding site for these proteins located at the distal end of each CUB1 module and stabilized by the Ca(2+) ion.

Amino Acid Sequence↗

PubMed1983

Adult transplantation tolerance induced by lentil lectin. III. Induction of transplantation tolerance by lentil lectin in mouse strain combinations with different H-2 disparities: tolerogenic effect of H-2D region antigens.

The survival time of skin allografts was investigated in 28 combinations of mouse strains differing at various loci, in adult recipients treated with lentil seed lectin (LCA). The recipients were given 1 mg of LCA daily (i.v. or i.p.) after transplantation of the skin graft. The immunosuppressive effect of LCA was generally inversely related to the conventional strength of the allotransplantation reaction, i.e. the rate of rejection of allografts on untreated recipients. In the case of H-2D antigenic disparities, the grafts usually survived for more than 100 days. The H-2A or H-2K disparity appeared to be relatively resistant to induction of tolerance by LCA treatment. The relative resistance of various H-2 antigens toward the induction of tolerance by LCA differs to some extent from that observed in experiments on the induction of neonatal tolerance by semiallogeneic lymphocytes as described in literature.

Animals↗

PubMed2001

[Frequency of the common cold in healthy subjects during exposure to a lectin-rich and a lectin-poor mistletoe preparation in a randomized, double-blind, placebo-controlled study].

BACKGROUND/OBJECTIVE: Mistletoe preparations have immunomodulatory properties in vitro and in vivo. We wanted to investigate whether or not these properties have an effect on the frequency of the common cold in healthy subjects. PROBANDS AND METHODS: During a randomized, placebo-controlled, double-blind study 16 volunteers received the mistletoe lectin(ML)-poor preparation Iscador Pini(R) (IP), 16 the ML-rich preparation Iscador Quercus spezial(R) (IQ), and 16 placebo (physiological saline solution) twice a week subcutaneously for 12 weeks. Weekly during weeks 1-12 and finally at week 26, a careful history of common cold symptoms was taken. Because the frequency of the common cold was not the main outcome criterion in this study, the number of cases needed to treat was not adjusted to this criterion. RESULTS: The mean frequency of the common cold during the 12 weeks of injection was 1.5 in the placebo, 1.4 in the IP and 1.1 in the IQ group. During this period in 2.3 (placebo), 1.9 (IP) and 1.4 (IQ) weeks symptoms of common cold were present. The difference in favor to IQ lasted until the end of the observation period in week 26. It was, however, not significant. Leukocyte and granulocyte count as well as C-reactive protein were not different between the groups. CONCLUSIONS: The study showed a trend (p = 0.4, exact Kruskal- Wallis test) to reduced frequency and duration of the common cold in subjects who were exposed to IQ.

Adult↗

PubMed1986

The affinity of the lectins Ricinus communis and Glycine maxima to carbohydrates on the cell surface of various forms of Trypanosoma cruzi and Trypanosoma rangeli, and the application of these lectins for the identification of T. cruzi in the feces of Rhodnius prolixus.

Flagellates of Trypanosoma cruzi (stock Molino 1), obtained from the intestine of experimentally infected Rhodnius prolixus, grown in cellular or acellular culture, as well as from the blood of infected mice, were examined by a direct fluorescence test using the lectins RCA (Ricinus communis-120) and SBA (soy bean agglutinin; Glycine maxima), conjugated with fluorescein isothiocyanate, for the detection of beta-D-galactose and alpha,beta-N-acetyl-D-galactosamine on the membranes of the flagellates. The same reactions were carried out using Trypanosoma rangeli (stock San Agustin), obtained from the intestine, hemo-lymph or salivary glands of experimentally infected R. prolixus, as well as from cultures and from the blood of experimentally infected CFW mice. The results indicate that the membrane of T. rangeli in the salivary glands of the vector contains beta-D-galactose, but that this sugar is absent from all other developmental stages of this trypanosome. All stages of intestinal and cultured. T. cruzi presented positive reactions with RCA-FITC and SBA-FITC. The high specificity of this technique makes it useful for the examination of R. prolixus, previously used in xenodiagnosis of Chagas' disease and for the examination of intradomiciliary or sylvatic vectors in epidemiological surveys in areas where T. cruzi and T. rangeli coexist. Formaldehyde fixed samples can be examined months later and false reports due to T. rangeli can be avoided.

Animals↗

PubMed1983

Adult transplantation tolerance induced by lentil lectin. I. The fate of tolerogenic lentil seed lectin after injection into mice.

Intravenous administration of lentil lectin is more efficient in the induction of transplantation tolerance to mouse skin allograft than intraperitoneal or subcutaneous administration. 131I-labelled LCA is eliminated relatively rapidly from the mouse body after i.v. injection (approximately 80% of a 1 mg dose eliminated after 48 h); LCA administered i.p. or s.c. is eliminated 2-3 times more slowly. The rate of elimination of LCA administered i.v. is only slightly lower than that of bovine serum albumin. Tolerogenic treatment by multiple i.p. or i.p. + i.v. doses of LCA only elicited a relatively low level of anti-LCA antibodies in the sera of recipients. Both LCA and BSA were distributed relatively homogeneously throughout the body but increased amounts of LCA were accumulated in the spleen, lymph nodes and lung.

Animals↗

PubMed1993

Probing the functions of endogenous lectins: effects of a monoclonal antibody against the neural crest-stage lectin of Xenopus laevis on trunk development.

Trunk neural crest of Xenopus laevis has been confronted prior to migration with whole or fragments of a monoclonal antibody raised against the carbohydrate-binding site of the endogenous neural crest-stage galactoside binding lectin (Milos et al.: Anat. Embryol., 182:319-327 '90). External fin formation was inhibited in confronted regions but extensive internal matrix develops suggesting interiorization of fin tissue. In the regions of missing fin, the myotomes overgrew the neural tube and dorsal root ganglion neuronal numbers became more variable. Melanophore numbers in regions of missing fin did not change but a significantly greater proportion of the pigment cells localized on the muscle surface that had overgrown the neural tube suggesting that the pigment cell population redistributed itself to occupy a greater myotomal area.

Animals↗

PubMed2003

Evolutionary analysis reveals collective properties and specificity in the C-type lectin and lectin-like domain superfamily.

Members of the C-type lectin/C-type lectin-like domain (CTL/CTLD) superfamily share a common fold and are involved in a variety of functions, such as generalized defense mechanisms against foreign agents, discrimination between healthy and pathogen-infected cells, and endocytosis and blood coagulation. In this work we used ConSurf, a computer program recently developed in our lab, to perform an evolutionary analysis of this superfamily in order to further identify characteristics of all or part of its members. Given a set of homologous proteins in the form of multiple sequence alignment (MSA) and an inferred phylogenetic tree, ConSurf calculates the conservation score in every alignment position, taking into account the relationships between the sequences and the physicochemical similarity between the amino acids. The scores are then color-coded onto the three-dimensional structure of one of the homologous proteins. We provide here and at http://ashtoret.tau.ac.il/ approximately sharon a detailed analysis of the conservation pattern obtained for the entire superfamily and for two subgroups of proteins: (a) 21 CTLs and (b) 11 heterodimeric CTLD toxins. We show that, in general, proteins of the superfamily have one face that is constructed mostly of conserved residues and another that is not, and we suggest that the former face is involved in binding to other proteins or domains. In the CTLs examined we detected a region of highly conserved residues, corresponding to the known calcium- and carbohydrate-binding site of the family, which is not conserved throughout the entire superfamily, and in the CTLD toxins we found a patch of highly conserved residues, corresponding to the known dimerization region of these proteins. Our analysis also detected patches of conserved residues with yet unknown function(s).

Amino Acid Sequence↗

PubMed1985

Lectins and lectin-like molecules in lower plants. II. Freshwater algae.

Freshwater chlamydomonad algae possess flagella surface isoagglutinins of a glycoprotein nature which are involved in gamete recognition and consequent cell fusion. Alternatively, such molecules may have a receptor role in certain Chlamydomonas species. In some freshwater volvocaines, lectin-like substances act as inducers of sexuality. At the moment it is speculative whether these materials can serve as naturally-occurring antibodies to protect algae from environmental antigens.

Chlamydomonas↗

PubMed1992

A possible calcium binding site in animal lectins: a 1H-NMR study of the interaction between lanthanides and a synthetic peptide from a highly conserved domain of Pleurodeles lectin.

1H-NMR techniques have been used to study the metal binding properties of a synthetic peptide of 15 amino acids corresponding to a highly conserved domain of Pleurodeles lectin. The addition of lanthanum chloride or praseodymium chloride in a peptide solution induces some conformational changes as displayed by several concerted variations of peptide resonances. The Ln3+ concentration dependence of the chemical shifts was used to calculate the Ln3+ binding constants. The dissociation constants of 95 microM and 280 microM were found for La3+ and Pr3+, respectively.

Amino Acid Sequence↗

PubMed1978

Studies on lectins. XL. O-glycosyl derivatives of Spheron in affinity chromatography of lectins.

Free monosaccharides can be used for direct glycosylation of Spheron, a spherical macroporous hydroxyalkyl methacrylate-ethylene dimethacrylate copolymer, in a reaction that proceeds at room temperature in dioxane medium under catalysis of dry HCl or BF3. Derivatives of L-fucose, D-galactose, D-glucose, D-mannose, N-acetyl-D-galactosamine and N-acetyl-D-glucosamine thus prepared from Spheron beads have been shown to be efficient affinity carriers in isolation of lectins from seeds of Canavalia ensiformis D.C. (concanavalin A), Dolichos biflorus L., Glycine soja (L.) Sieb. et Zucc., Lens esculenta Moench, Ricinus communis L., Ulex europaeus L. and from albumin glands of the garden snail Helix pomatia L.

Acrylic Resins↗

PubMed2003

Relation between recurrent vulvovaginal candidiasis, vaginal concentrations of mannose-binding lectin, and a mannose-binding lectin gene polymorphism in Latvian women.

Vaginal concentrations of mannose-binding lectin (MBL) and possession of a polymorphism in codon 54 of the MBL gene were determined in 42 women with recurrent vulvovaginal candidiasis (RVVC) and 43 control subjects. Reduced vaginal MBL levels and an increased occurrence of the polymorphism were present in women with RVVC.

Adolescent↗

PubMed1996

Humoral and mucosal IgA antibody response to a recombinant 52-kDa cysteine-rich portion of the Entamoeba histolytica galactose-inhibitable lectin correlates with detection of native 170-kDa lectin antigen in serum of patients with amebic colitis.

Humoral and mucosal IgA responses to a recombinant cysteine-rich portion (designated LC3) of the Entamoeba histolytica galactose-inhibitable lectin's 170-kDa subunit were determined in patients with amebic colitis. All patients had 170-kDa amebic antigen in serum, compared with 1 of 50 cyst passers and 1 of 31 controls (P < .01). Seven days after treatment, serum and fecal 170-kDa antigen became undetectable in 12 of the 13 patients (P < .001). Serum anti-LC3 IgA was found in 83.8% of colitis patients, compared with 2% of controls and 12% of asymptomatic cyst passers (P < .001). Salivary and fecal anti-LC3 IgA levels were higher in patients than in cyst passers (P < .001). In conclusion, in amebic colitis, development of humoral and mucosal IgA responses to the recombinant LC3-encoded protein correlates with detection of amebic 170-kDa antigen in serum and feces.

Animals↗

PubMed1998

Plant lectins - more than just tools for glycoscientists: occurrence, structure, and possible functions of plant lectins.

Plant lectins are easily available, fairly stable and suitable for many kinds of chemical modification. Thus, they have become important tools in glycosciences. In the present review, it is attempted to throw light upon aspects of lectinology that deal with their natural occurrence, biosynthesis, structure, binding specificities and hypotheses about their biological functions.

Binding Sites↗

PubMed1998

Biological activities of a novel lectin derived from silkworm faeces: characteristic changes of mouse peritoneal macrophages by the lectin.

A novel lectin derived from silkworm faeces, named NUE, activates phagocytosis of mouse peritoneal macrophages. At this time, significant morphological changes of the cells take place. NUE-treated macrophages formed projection-like neurocytes within 12 hr of treatment, and appeared somewhat flat in shape with the activation of cell growth. Associated with the morphological changes, actin was organized in dot-like structures corresponding to cell-substratum contact sites in NUE-treated macrophages. Vinculin, a cytoskeletal protein involved in microfilament-membrane interaction, formed doughnut-like rings matching the actin-dots, called "podosomes". Furthermore, observation by interference reflection microscopy showed that NUE-treated macrophages adhered more strongly to the substratum at local areas. According to these changes, more proteins associated with cell-substratum contact sites became to detergent-resistant. It was shown that NUE changed adhesive form of mouse peritoneal macrophages structurally and qualitatively.

Animals↗

PubMed1983

In situ-differentiation of lymphocytes in fixed tissues with peroxidase-labeled Helix pomatia lectin: revelation of the Helix pomatia lectin receptor on cell surfaces. Application in lymph node tissues and cutaneous lymphomas.

A receptor for Helix pomatia lectin (HPL) occurs on 71.5% of peripheral blood lymphocytes. With double incubation techniques we could show that the population of HPL-positive lymphocytes is by far (greater than 90%) identical with the population of T lymphocytes, as determined by "classical" markers (E rosetting) and newly developed T cell markers like OKT3 or anti-human Lyt3 monoclonal antibodies. In formaldehyde-fixed lymph node sections we could demonstrate the homing area of HPL-positive lymphocytes, the paracortical regions. Conventional histological counterstaining was readily possible. We have employed HPL-peroxidase for differentiation of lymphocytes in benign and malignant infiltrates in human skin. In reactive cutaneous infiltrates, as well as in cutaneous lymphomas, HPL-peroxidase staining allows a clear differentiation of the involved lymphatic cells, and may serve as a tumor marker in certain T lymphomas, where we could demonstrate the lymphoma cells to carry the HPL-receptor.

Cell Membrane↗

PubMed1993

Feed-induced lectins in piglets. Feed-induced lectins and their effect on post-weaning diarrhoea, daily weight gain and mortality.

The effect on various biological variables of a special weaner feed (FD) with the capacity to induce endogenous synthesis of feed induced lectins (FIL), and a commonly used commercial diet (CD) was evaluated in 891 piglets in four different experiments. The FD diet was found to induce a high activity of FIL (FIL = 0.94 +/- 0.03 units/ml. blood), as compared to CD (FIL < 0.20 units/ml. blood). The FIL values did not decrease after weaning. The incidence of diarrhoea in piglets fed FD 0-14 days post-weaning was 12 +/- 5 per cent, as compared to 41 +/- 9 per cent in the CD group, the difference being significant. Daily weight gain 0-35 days after weaning was 67 +/- 15 grams greater in the FD group than among those fed CD. The consumption of FD was double that of CD in the period before weaning (at 5 weeks), and some 40 per cent more in the postweaning period up to 9 weeks of age.

Animal Feed↗

PubMed1999

Molten globule-like state of peanut lectin monomer retains its carbohydrate specificity. Implications in protein folding and legume lectin oligomerization.

A central question in biological chemistry is the minimal structural requirement of a protein that would determine its specificity and activity, the underlying basis being the importance of the entire structural element of a protein with regards to its activity vis à vis the overall integrity and stability of the protein. Although there are many reports on the characterization of protein folding/unfolding intermediates, with considerable secondary structural elements but substantial loss of tertiary structure, none of them have been reported to show any activity toward their respective ligands. This may be a result of the conditions under which such intermediates have been isolated or due to the importance of specific structural elements for the activity. In this paper we report such an intermediate in the unfolding of peanut agglutinin that seems to retain, to a considerable degree, its carbohydrate binding specificity and activity. This result has significant implications on the molten globule state during the folding pathway(s) of proteins in general and the quaternary association in legume lectins in particular, where precise subunit topology is required for their biologic activities.

Binding Sites↗

PubMed1978

Lectin studies. III. A survey of phytohemagglutinins: interaction of lectins with erythrocytes of ten vertebrate species.

Extracts of seeds from 79 plant species were tested for agglutinating and lytic activity with the red cells of ten vertebrate species (man, monkey, rabbit, rat, goat, sheep, guinea pig, horse, fowl, dog). Of these extracts, 24 were hemagglutinating and 15 were hemolytic. The results suggest that some lectins can serve as useful diagnostic reagents in distinguishing the blood of one animal species from that of another.

Animals↗