RESUMO
Cells use glycans to encode information that modulates processes ranging from cell-cell recognition to programmed cell death. This information is encoded within a glycocode, and its decoding is performed by carbohydrate-binding proteins. Among these, lectins stand out due to their specific and reversible interaction with carbohydrates. Changes in glycosylation patterns are observed in several pathologies, including cancer, where abnormal glycans are found on the surfaces of affected tissues. Given the importance of the bioprospection of promising biomolecules, the current work aimed to determine the structural properties and anticancer potential of the mannose-specific lectin from seeds of Canavalia villosa (Cvill). Experimental elucidation of the primary and 3D structures of the lectin, along with glycan array and molecular docking, facilitated the determination of its fine carbohydrate-binding specificity. These structural insights, coupled with the lectin's specificity, have been combined to explain the antiproliferative effect of Cvill against cancer cell lines. This effect is dependent on the carbohydrate-binding activity of Cvill and its uptake in the cells, with concomitant activation of autophagic and apoptotic pathways.
Assuntos
Canavalia , Lectinas , Lectinas/farmacologia , Lectinas/análise , Canavalia/metabolismo , Simulação de Acoplamento Molecular , Lectinas de Plantas/metabolismo , Sementes/metabolismo , Carboidratos/análise , Polissacarídeos/análiseRESUMO
Different degrees in the biological activities of Canavalia rosea had been previously reported . In this study, our group assessed the cardioprotective effects of the ethyl acetate fraction (EAcF) of the Canavalia rosea leaves. Firstly, it was confirmed, by in vitro approach, that the EAcF has high antioxidant properties due to the presence of important secondary metabolites, as flavonoids. In order to explore their potential protector against cardiovascular disorders, hearts were previously perfused with EAcF (300 µg.mL-1) and submitted to the global ischemia followed by reperfusion in Langendorff system. The present findings have demonstrated that EAcF restored the left ventricular developed pressure and decreased the arrhythmias severity index. Furthermore, EAcF significantly increased the glutathiones peroxidase activity with decreased malondialdehyde and creatine kinase levels. EAcF was effective upon neither the superoxide dismutase, glutationes reductase nor the catalase activities. In addition, the Western blot analysis revealed that ischemia-reperfusion injury significantly upregulates caspase 3 protein expression, while EAcF abolishes this effect. These results provide evidence that the EAcF reestablishes the cardiac contractility and prevents arrhythmias; it is suggested that EAcF could be used to reduce injury caused by cardiac reperfusion. However more clinical studies should be performed, before applying it in the clinic.
Assuntos
Antioxidantes , Traumatismo por Reperfusão Miocárdica , Ratos , Animais , Humanos , Antioxidantes/farmacologia , Antioxidantes/metabolismo , Traumatismo por Reperfusão Miocárdica/metabolismo , Canavalia/metabolismo , Ratos Sprague-Dawley , Superóxido Dismutase/metabolismo , Folhas de Planta/metabolismo , Miocárdio/metabolismoRESUMO
Helicobacter pylori and Cryptococcus ssp. are pathogenic ureolytic microorganisms that cause several disorders in the host organism and, in severe cases, lead to death. Both infections have the urease enzyme as a key virulence factor since they use its ability to produce ammonia to soften the inhospitable pH to which they are subjected. In this review, we describe two ureases as possible molecular targets for drug discovery and provide insights for developing potent inhibitors against ureases from these pathogenic microorganisms through computer-aided drug discovery approaches, such as structure-based drug design (SBDD) and structure-activity relationship (SAR). The SAR studies have indicated several essential subunits and groups to be present in urease inhibitors that are critical for inhibitory activity against H. pylori or Cryptococcus spp. Since the threedimensional structure of C. neoformans urease has yet to be determined experimentally, the plant urease of Canavalia ensiformis was used in this study due to its structural similarity. Therefore, in the SBDD context, FTMap and FTSite analyses were performed to reveal characteristics of the urease active sites in two protein data bank files (4H9M, Canavalia ensiformis, and 6ZJA, H. pylori). Finally, a docking-based analysis was performed to explore the best inhibitors described in the literature to understand the role of the ligand interactions with the key residues in complex ligand-urease stabilization, which can be applied in the design of novel bioactive compounds.
Assuntos
Cryptococcus neoformans , Helicobacter pylori , Humanos , Urease/química , Urease/metabolismo , Cryptococcus neoformans/metabolismo , Ligantes , Canavalia/metabolismoRESUMO
Lectins participate in the defense against microorganisms and in signaling the damage caused by pathogens to the cell surface and/or intracellular in plants. This study aims to analyze the antifungal potential of lectins extracted from seeds of Canavalia ensiformis (L.) DC and Canavalia rosea (Sw.) DC, against Candida albicans and Candida tropicalis. The antimicrobial tests were performed by microdilution against Candida spp. The test to verify the combined lectin/fluconazole effect was performed using subinhibitory concentrations of lectins and with antifungal ranging from 0.5 to 512 µg/mL. The ability to inhibit the morphological transition of Candida spp. was evaluated by microcultivation in a moist chamber. The results of the minimum inhibitory concentration revealed no antifungal activity against the tested strains. However, lectins modified the action of fluconazole, reducing the IC50 of the drug against C. albicans. Lectins were also able to discretely modulate the morphological transition of the tested strains.
Assuntos
Candida albicans , Candida tropicalis , Antifúngicos/farmacologia , Canavalia/metabolismo , Candida/metabolismo , Concanavalina A , Fluconazol/farmacologia , Lectinas/farmacologia , Testes de Sensibilidade Microbiana , PlânctonRESUMO
Phytoremediation is an alternative for remediating soil contamination by copper, and its efficiency has been shown to increase when arbuscular mycorrhizal fungi (AMF) and earthworms are separately inoculated into the soil. This study evaluated the isolated and combined effects of inoculating earthworms and arbuscular mycorrhizal fungi into a sandy soil on copper phytoremediation by Canavalia ensiformis. The plants were grown in a greenhouse in soil contaminated with 100â¯mg Cu kg-1 with and without being inoculated with the arbuscular mycorrhizal fungus Rhizoglomus clarum and the earthworm Eisenia andrei. The availabilities of solid-phase Cu and other nutrients in the soil solution and plant growth were evaluated along with Cu phytotoxicity based on photochemical efficiency and oxidative stress enzyme activity. Accumulation of Cu and other nutrients in the shoots and roots; mycorrhizal colonization, nodulation, and reproduction; and Cu accumulation in the earthworm tissues were also evaluated. The copper caused photosynthetic and biochemical damage that reduced the shoot dry weight by 44% and the root dry weight by 29%. However, the arbuscular mycorrhizal fungus alleviated the Cu toxicity to the plant and increased the shoot dry weight by 81% in the contaminated soil. The earthworms increased the Cu uptake and translocation to the shoot by 31%. The combined presence of the arbuscular mycorrhizal fungus and earthworms in the contaminated soil increased the growth and Cu content of the aerial plant tissues, yielding a 200% increase in Cu accumulation (metal contentâ¯×â¯biomass) in the C. ensiformis shoots. Combined inoculation with earthworms and arbuscular mycorrhizal fungi increased copper phytoextraction by Canavalia ensiformis in a sandy soil.
Assuntos
Canavalia/metabolismo , Cobre/análise , Glomeromycota/metabolismo , Micorrizas/metabolismo , Oligoquetos/metabolismo , Poluentes do Solo/análise , Animais , Biodegradação Ambiental , Biomassa , Canavalia/crescimento & desenvolvimento , Glomeromycota/crescimento & desenvolvimento , Micorrizas/crescimento & desenvolvimento , Solo/químicaRESUMO
Heavy metals in soil are naturally occurring but may be enhanced by anthropogenic activities such as mining. Bio-accumulation of heavy metals in the food chain, following their uptake to plants can increase the ecotoxicological risks associated with remediation of contaminated soils using plants. In the current experiment sugar cane straw-derived biochar (BC), produced at 700 °C, was applied to a heavy metal contaminated mine soil at 1.5%, 3.0% and 5.0% (w/w). Jack bean (Canavalia ensiformis) and Mucuna aterrima were grown in pots containing soil and biochar mixtures, and control pots without biochar. Pore water was sampled from each pot to confirm the effects of biochar on metal solubility, whilst soils were analyzed by DTPA extraction to confirm available metal concentrations. Leaves were sampled for SEM analysis to detect possible morphological and anatomical changes. The application of BC decreased the available concentrations of Cd, Pb and Zn in 56, 50 and 54% respectively, in the mine contaminated soil leading to a consistent reduction in the concentration of Zn in the pore water (1st collect: 99 to 39 µg L(-1), 2nd: 97 to 57 µg L(-1) and 3rd: 71 to 12 µg L(-1)). The application of BC reduced the uptake of Cd, Pb and Zn by plants with the jack bean translocating high proportions of metals (especially Cd) to shoots. Metals were also taken up by Mucuna aterrima but translocation to shoot was more limited than for jack bean. There were no differences in the internal structures of leaves observed by scanning electron microscopy. This study indicates that biochar application during mine soil remediation reduce plant concentrations of potential toxic metals.
Assuntos
Cádmio/farmacocinética , Carvão Vegetal , Chumbo/farmacocinética , Poluentes do Solo/farmacocinética , Zinco/farmacocinética , Brasil , Cádmio/análise , Canavalia/efeitos dos fármacos , Canavalia/metabolismo , Carvão Vegetal/farmacologia , Chumbo/análise , Microscopia Eletrônica de Varredura , Mineração , Mucuna/efeitos dos fármacos , Mucuna/metabolismo , Fósforo/farmacocinética , Folhas de Planta/química , Potássio/farmacocinética , Solo/química , Poluentes do Solo/análise , Zinco/análiseRESUMO
Among the technologies used to recuperate cadmium (Cd) contaminated soils, phytoextraction are particularly important, where the selection of suitable plants is critical to the success of the soil remediation. Thus, the objectives of this study were to evaluate the responses of jack-bean and sorghum to Cd supply and to quantify Cd accumulation by these species grown in hydroponic culture. The plants were subjected to 0, 15, 30, or 60 µmol Cd L(-1) in the nutrient solution, and gas exchange, plant growth and Cd accumulation were measured at 25 days after starting Cd treatments. The Cd supply severely reduced growth of shoots and roots in both species. In jack-bean, Cd decreased photosynthesis by 56-86%, stomatal conductance by 59-85% and transpiration by 48-80%. The concentrations and amounts of Cd accumulated in the plant tissues were proportional to the metal supply in the nutrient solution. Sorghum was more tolerant than jack-bean to Cd toxicity, but the latter showed a greater metal concentration and accumulation in the shoot. Therefore, jack-bean would be more suitable than sorghum for use in Cd phytoremediation programs based on phytoextraction.
Assuntos
Cádmio/metabolismo , Canavalia/metabolismo , Recuperação e Remediação Ambiental/métodos , Sorghum/metabolismo , Biodegradação Ambiental , Cádmio/análise , Canavalia/química , Recuperação e Remediação Ambiental/instrumentação , Hidroponia , Sorghum/químicaRESUMO
Ureases catalyze the hydrolysis of urea into NH3 and CO2. They are synthesized by plants, fungi and bacteria but not by animals. Ureases display biological activities unrelated to their enzymatic activity, i.e., platelet and neutrophil activation, fungus inhibition and insecticidal effect. Urease from Canavalia ensiformis (jack bean) is toxic to several hemipteran and coleopteran insects. Jaburetox is an insecticidal fragment derived from jack bean urease. Among other effects, Jaburetox has been shown to interact with lipid vesicles. In this work, the ion channel activity of C. ensiformis urease, Jaburetox and three deletion mutants of Jaburetox (one lacking the N-terminal region, one lacking the C-terminal region and one missing the central ß-hairpin) were tested on planar lipid bilayers. All proteins formed well resolved, highly cation-selective channels exhibiting two conducting states whose conductance ranges were 7-18pS and 32-79pS, respectively. Urease and the N-terminal mutant of Jaburetox were more active at negative potentials, while the channels of the other peptides did not display voltage-dependence. This is the first direct demonstration of the capacity of C. ensiformis urease and Jaburetox to permeabilize membranes through an ion channel-based mechanism, which may be a crucial step of their diverse biological activities, including host defense.
Assuntos
Canavalia/metabolismo , Inseticidas/metabolismo , Canais Iônicos/metabolismo , Bicamadas Lipídicas/metabolismo , Peptídeos/metabolismo , Proteínas de Plantas/metabolismo , Urease/metabolismo , Sequência de Aminoácidos , Canavalia/química , Canavalia/genética , Permeabilidade da Membrana Celular , Inseticidas/química , Dados de Sequência Molecular , Peptídeos/química , Peptídeos/genética , Proteínas de Plantas/química , Proteínas de Plantas/genética , Deleção de Sequência , Urease/química , Urease/genéticaRESUMO
Indole-3-acetic acid (IAA) bound is considered a storage molecule and is inactive. However, some studies have proposed an additional possible regulatory mechanism based on the ability of lectins to form complexes with IAA. We report the first crystal structure of ConM in complex with IAA at 2.15 Å resolution. Based on a tetrameric model of the complex, we hypothesize how the lectin controls the availability of IAA during the early seedling stages, indicating a possible new physiological role for these proteins. A free indole group is also bound to the protein. The ConM interaction with different forms of IAA is a strategy to render the phytohormone unavailable to the cell. Thus, this new physiological role proposed for legume lectins might be a novel mechanism by which IAA levels are decreased in addition to the destruction and formation of new complexes in the later stages of seed germination.
Assuntos
Canavalia/fisiologia , Ácidos Indolacéticos/metabolismo , Lectinas de Plantas/metabolismo , Sementes/metabolismo , Animais , Canavalia/metabolismo , Hemaglutinação/efeitos dos fármacos , Simulação de Acoplamento Molecular , Lectinas de Plantas/química , Lectinas de Plantas/farmacologia , Ligação Proteica , Conformação Proteica , CoelhosRESUMO
Soil contamination by heavy metals is a serious problem to humans due to its high level of toxicity. The heavy metal lead (Pb) is commonly used in industries and if the disposal of residues that contain this element is not done properly may result in tragic consequences to the organisms. In this experiment we assessed the potential of a forrage leguminous, Canavalia gladiata, to phytoremediate lead-contaminated soil under mycorrhizal influence. The experimental design was composed of 4 Pb doses (0, 250, 500, and 1000 mg kg(-1) of soil) and the plants were inoculated or uninoculated with arbuscular mycorrhizal fungi (AMF). We observed that the nodulation was severely affected by the presence of Pb independently of the mycorrhizal status; most of the elements analyzed were affected independently of the mycorrhizal status with exception of P. The mycorrhizal colonization was able to restrict the entrance of Pb in plants under high concentrations of Pb but promoted it's accumulation in both organs under intermediate concentrations of this element. Besides the mycorrhization did not promote plant growth under Pb stress, the use of this plant may be considered to be used for phytostabilization purposes.
Assuntos
Canavalia/metabolismo , Canavalia/microbiologia , Glomeromycota/fisiologia , Chumbo/metabolismo , Micorrizas/fisiologia , Solo/química , Biodegradação Ambiental , Biomassa , Canavalia/crescimento & desenvolvimento , Germinação , Glomeromycota/crescimento & desenvolvimento , Ferro/análise , Ferro/metabolismo , Chumbo/análise , Micorrizas/crescimento & desenvolvimento , Fósforo/análise , Fósforo/metabolismo , Nodulação , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Raízes de Plantas/microbiologia , Brotos de Planta/crescimento & desenvolvimento , Brotos de Planta/metabolismo , Brotos de Planta/microbiologia , Distribuição Aleatória , Sementes/crescimento & desenvolvimento , Sementes/metabolismo , Sementes/microbiologia , Poluentes do Solo/análise , Poluentes do Solo/metabolismo , Enxofre/análise , Enxofre/metabolismo , Simbiose , Zinco/análise , Zinco/metabolismoRESUMO
The immobilization of the glucose/mannose-binding lectin from Concanavalia ensiformis seeds (ConA) onto a monolayer made of a galactomannan extracted from Leucaena leucocephala seeds (GML), which was adsorbed onto - amino-terminated surfaces, was investigated by means of ellipsometry and atomic force microscopy. The mean thickness of GML monolayer, which polysaccharide consists of linear 1â4-linked ß-D-mannopyranosil units partially substituted at C-6 by α-D-galactopyranosyl units, amounted to (1.5±0.2) nm. ConA molecules adsorbed onto GML surfaces forming (2.0±0.5) nm thick layers. However, in the presence of mannose the adsorption failed, indicating that ConA binding sites were blocked by mannose and were no longer available for mannose units present in the GML backbone. The GML film was also used as support for the adsorption of three serotypes of dengue virus particles (DENV-1, DENV-2 and DENV-3), where DENV-2 formed the thickest film (4±2) nm. The adsorbed layer of DENV-2 onto ConA-covered GML surfaces presented mean thickness values similar to that determined for DENV-2 onto bare GML surfaces. The addition of free mannose units prevented DENV-2 adsorption onto ConA-covered GML films by ~50%, suggesting competition between virus and mannose for ConA binding sites. This finding suggests that if ConA is also adsorbed to GML surface and its binding site is blocked by free mannose, virus particles are able to recognized GML mannose unities substituted by galactose. Interactions between polysaccharides thin films, proteins, and viruses are of great relevance since they can provide basis for the development of biotechnological devices. These results indicate that GML is a potential polysaccharide for biomaterials development, as those could involve interactions between ConA in immune system and viruses.
Assuntos
Concanavalina A/química , Vírus da Dengue/metabolismo , Mananas/química , Adsorção , Animais , Sítios de Ligação , Materiais Biocompatíveis/química , Canavalia/metabolismo , Fabaceae/metabolismo , Galactose/análogos & derivados , Humanos , Ligação de Hidrogênio , Lectinas/química , Substâncias Macromoleculares/química , Manose/química , Microscopia de Força Atômica/métodos , Polissacarídeos/química , Propriedades de SuperfícieRESUMO
Diocleinae lectins are highly homologous in their primary structure which features metal binding sites and a carbohydrate recognition domain (CRD). Differences in the biological activity of legume lectins have been widely investigated using hemagglutination inhibition assays, isothermal titration microcalorimetry and co-crystallization with mono- and oligosaccharides. Here we report a new lectin crystal structure (ConBr) extracted from seeds of Canavalia brasiliensis, predict dimannoside binding by docking, identify the α-aminobutyric acid (Abu) binding pocket and compare the CRD of ConBr to that of homologous lectins. Based on the hypothesis that the carbohydrate affinity of lectins depends on CRD configuration, the relationship between tridimensional structure and endothelial NO synthase activation was used to clarify differences in biological activity. Our study established a correlation between the position of CRD amino acid side chains and the stimulation of NO release from endothelium.
Assuntos
Canavalia/metabolismo , Óxido Nítrico Sintase Tipo III/química , Lectinas de Plantas/química , Carboidratos , Cristalografia por Raios X , Ativação Enzimática , Conformação ProteicaRESUMO
Jack bean (Canavalia ensiformis) seeds are toxic for insects and the toxicity is due in part to an entomotoxic peptide enzymatically released from ureases in the midgut of susceptible insects. To characterize expression of urease isoforms in jack bean seed, particularly the more abundant urease isoform (JBU), quantitative proteomics was performed. Quiescent through 5-day germinating seeds were analyzed at 1-day intervals using a total proteomics approach (TPA) and also after co-immunoprecipitation (co-IP) with anti-JBU monoclonal antibodies. Jack bean proteins for TPA and co-IP were pre-fractionated by SDS-PAGE, segmented for in-gel trypsin digestion, and analyzed by liquid chromatography coupled to nanospray ionization tandem mass spectrometry (LC-MS/MS). Acquired MS(2) data were searched against a comprehensive plant database and the MEROPS peptidase database, in the absence of a jack bean EST database. Proteins detected in TPA were quantified by label-free spectral counting. A total of 234 and 106 non-redundant proteins were detected in TPA and co-IP, respectively. Mobilization of JBU was observed beginning 3-days after imbibition indicating that the entomotoxic peptide was not formed before this stage. A predicted urease isoform, JBURE-IIb, was detected in the co-IP study. Additionally, 46 plastid proteins, including RuBisCO and plastid ATPase were pulled down with JBU antibodies. These data shed new light on the behavior of urease isoforms during the early stages of plant development.
Assuntos
Canavalia/metabolismo , Proteínas de Plantas/metabolismo , Proteômica/métodos , Plântula/metabolismo , Sequência de Aminoácidos , Canavalia/crescimento & desenvolvimento , Cromatografia Líquida , Eletroforese em Gel de Poliacrilamida , Imunoprecipitação , Isoenzimas/metabolismo , Dados de Sequência Molecular , Proteínas de Plantas/isolamento & purificação , Transporte Proteico , Plântula/crescimento & desenvolvimento , Espectrometria de Massas por Ionização por Electrospray , Espectrometria de Massas em Tandem , Urease/metabolismoRESUMO
The influence of arbuscular mycorrhizal fungi (AMF) inoculation on Canavalia ensiformis growth, nutrient and Zn uptake, and on some physiological parameters in response to increasing soil Zn concentrations was studied. Treatments were applied in seven replicates in a 2 x 4 factorial design, consisting of the inoculation or not with the AMF Glomus etunicatum, and the addition of Zn to soil at the concentrations of 0, 100, 300 and 900 mg kg(-1). AMF inoculation enhanced the accumulation of Zn in tissues and promoted biomass yields and root nodulation. Mycorrhizal plants exhibited relative tolerance to Zn up to 300 mg kg(-1) without exhibiting visual symptoms of toxicity, in contrast to non-mycorrhizal plants which exhibited a significant growth reduction at the same soil Zn concentration. The highest concentration of Zn added to soil was highly toxic to the plants. Leaves of plants grown in high Zn concentration exhibited a Zn-induced proline accumulation and also an increase in soluble amino acid contents; however proline contents were lower in mycorrhizal jack beans. Plants in association or not with the AMF exhibited marked differences in the foliar soluble amino acid profile and composition in response to Zn addition to soil. In general, Zn induced oxidative stress which could be verified by increased lipid peroxidation rates and changes in catalase, ascorbate peroxidase, glutathione reductase and superoxide dismutase activities. In summary, G. etunicatum was able to maintain an efficient symbiosis with jack bean plants in moderately contaminated Zn-soils, improving plant performance under those conditions, which is likely to be due to a combination of physiological and nutritional changes caused by the intimate relation between fungus and plant. The enhanced Zn uptake by AMF inoculated jack bean plants might be of interest for phytoremediation purposes.
Assuntos
Canavalia/metabolismo , Micorrizas/metabolismo , Microbiologia do Solo , Poluentes do Solo/metabolismo , Zinco/metabolismo , Antioxidantes/metabolismo , Biodegradação Ambiental , Canavalia/crescimento & desenvolvimento , Canavalia/microbiologia , Folhas de Planta/metabolismo , Proteínas de Plantas/metabolismo , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Raízes de Plantas/microbiologia , Poluentes do Solo/toxicidade , Zinco/toxicidadeRESUMO
Canavalia ensiformis ureases are toxic to insects of different orders. The entomotoxicity of urease is due to a 10 kDa internal peptide released by proteinases in the insect digestive tract. We previously observed that, given orally, urease is toxic to nymphs of Dysdercus peruvianus, but does not affect adults. Here we characterized the major proteolytic activities of D. peruvianus midgut homogenates and investigated their in vitro-catalyzed release of the 10 kDa entomotoxic peptide from urease. Cysteine, aspartic and metalloproteinases are present in both homogenates. Variations in optimal pH and susceptibility to inhibitors indicated differences in the enzyme profiles in the two developmental stages. Only nymph homogenates released approximately 10 kDa fragment(s) from urease, recognized by antibodies against the entomotoxic peptide. Fluorogenic substrates containing urease partial sequences flanking the N-terminal or the C-terminal portion of the entomotoxic peptide were efficiently cleaved by homogenates from nymphs, but much more slowly by the adult homogenate. Different classes of enzymes in the homogenates cleaved both substrates suggesting that in vivo the release of the entomotoxic peptide results from the concerted action of at least two different proteinases. Our findings support the view that a differential processing of ingested urease by the insects explains at least in part the lack of toxicity in adults.
Assuntos
Canavalia/metabolismo , Heterópteros/enzimologia , Proteínas de Insetos/fisiologia , Peptídeo Hidrolases/fisiologia , Toxinas Biológicas/metabolismo , Urease/metabolismo , Animais , Caseínas/metabolismo , Cromatografia Líquida , Heterópteros/crescimento & desenvolvimento , Hidrólise , Proteínas de Insetos/metabolismo , Ninfa/enzimologia , Ninfa/crescimento & desenvolvimento , Peptídeo Hidrolases/metabolismo , Espectrometria de Massas por Ionização por ElectrosprayRESUMO
Plant lectins, especially those purified from species of the Leguminosae family, represent the best studied group of carbohydrate-binding proteins. The legume lectins from Diocleinae subtribe are highly similar proteins that present significant differences in the potency/efficacy of their biological activities. The structural studies of the interactions between lectins and sugars may clarify the origin of the distinct biological activities observed in this high similar class of proteins. In this way, this work presents a crystallographic study of the ConM and CGL (agglutinins from Canavalia maritima and Canavalia gladiata, respectively) in the following complexes: ConM/CGL:Man(alpha1-2)Man(alpha1-O)Me, ConM/CGL:Man(alpha1-3)Man(alpha1-O)Me and ConM/CGL:Man(alpha1-4)Man(alpha1-O)Me, which crystallized in different conditions and space group from the native proteins. The structures were solved by molecular replacement, presenting satisfactory values for R(factor) and R(free). Comparisons between ConM, CGL and ConA (Canavalia ensiformis lectin) binding mode with the dimannosides in subject, presented different interactions patterns, which may account for a structural explanation of the distincts biological properties observed in the lectins of Diocleinae subtribe.
Assuntos
Bioquímica/métodos , Canavalia/metabolismo , Lectinas/química , Manosídeos/química , Sítios de Ligação , Carboidratos/química , Cristalização , Elétrons , Histidina/química , Manose/química , Modelos Químicos , Conformação Molecular , Proteínas/química , Termodinâmica , Água/químicaRESUMO
The crystal structure of Canavalia maritima lectin (ConM) complexed with trehalose and maltose revealed relevant point mutations in ConA-like lectins. ConM with the disaccharides and other ConA-like lectins complexed with carbohydrates demonstrated significant differences in the position of H-bonds. The main difference in the ConM structure is the replacement of Pro202 by Ser202, a residue that promotes the approximation of Tyr12 to the carbohydrate-binding site. The O-6' of the second glucose ring in maltose interacts with Tyr12, while in trehalose the interaction is established by the O-2' and Tyr12, explaining the higher affinity of ConM for disaccharides compared to monosaccharides.
Assuntos
Canavalia/metabolismo , Concanavalina A/química , Cristalografia por Raios X/métodos , Lectinas/química , Maltose/química , Trealose/química , Sítios de Ligação , Carboidratos/química , Elétrons , Ligação de Hidrogênio , Conformação Molecular , Mutação , Conformação Proteica , SoftwareRESUMO
The lectin from the seeds of Canavalia ensiformis (ConA) and Dioclea guianensis (DguiL) was tested upon its renal effects using the isolated perfusion rat kidney method. Both lectins (10 microg/ml) affected perfusion pressure and renal vascular resistance, but DguiL showed a much greater action than ConA. However, ConA, but not DguiL, affected potassium tubular transport.