Interactions between indole-3-acetic acid (IAA) with a lectin from Canavalia maritima seeds reveal a new function for lectins in plant physiology

AbstractIndole-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

Estudios estructurales de lectinas de algas marinas y de vegetales superiores

Tesis doctoral del Departamento de Bioquímica y Biología Molecular, Universitat de ValènciaPeer reviewe

Purification and enzymatic properties of a textile dye-decolourizing peroxidase from Moringa oleifera roots / Purificação e propriedades enzimáticas de uma peroxidase descorante de corantes têxteis a partir de raízes de Moringa oleifera

Peroxidases are ubiquitous enzymes involved in the oxidation of a variety of aromatic substrates including textile dyes, which are harmful for aquatic life and human health. Hence, the present study describes the purification of a peroxidase, named MoPOX, from Moringa oleifera roots using DEAE-Sephacel and gel filtration chromatography on a Superdex® 75 column. The peptide sequences recorded by mass spectrometry analysis confirmed the identity of MoPOX with other plant peroxidases. The optimum pH and temperature of enzyme activity were 5.2 and 70 °C, respectively. Its enzymatic activity in the presence of metal ions and classical peroxidase inhibitors was also evaluated. MoPOX follows Michaelis-Menten kinetics, with specificity, in ascending order, to the substrates ABTS eugenol O-dianisidine ≅ guaiacol, besides being highly thermostable. The purified peroxidase (0.015, 0.030 or 0.150 mg/mL) degraded different dyes (50 or 100 mg/L), such as Remazol® Blue RGB, Remazol® Navy RGB and Telon® Turquoise M-5G 85%. Decolorization rates varied from 15 to 90% depending on the dye concentration, enzyme concentration and exposure time. MoPOX is the first peroxidase purified from M. oleifera roots, and the results showed it has biotechnological potential for biodegradation of hazardous compounds.

A new mucin-binding lectin from the marine sponge Aplysina fulva (AFL) exhibits antibiofilm effects

A new mucin-binding lectin (AFL) was isolated from the marine sponge Aplysina fulva. AFL was purified by affinity chromatography on Sepharose™ matrix. Its hemagglutinating activity was independent of divalent ions, and it was weakly inhibited by simple sugars. However, porcine stomach mucin was a powerful inhibitor. In SDS PAGE, piridylethylated AFL showed one band of approximately 16 kDa, whereas in the non-reducing conditions, AFL showed at least two bands of 30 and 70 kDa. Mass spectrometry MALDI-ToF analysis showed one major ion of 31,652 ± 5 Da, which corresponded to a dimer formed by subunits linked by disulfide bonds. The first fifteen amino acids of AFL were determined, and no sequence similarity was observed with any known protein. Internal sequences were obtained by mass spectrometry analysis of tryptic digestion of AFL spots. These peptides showed similarity with a lectin from marine sponge Aplysina lactuca. Secondary structure of AFL was predominantly formed by β-conformations, which were stable at variations of pH and temperature. AFL did not inhibit planktonic growth of Gram-positive and Gram-negative bacteria tested. However, the lectin did significantly reduce the biomass biofilm of the bacteria Staphylococcus aureus, S. epidermidis, and Escherichia coli

Crystallization and preliminary X-ray diffraction analysis of the lectin from Canavalia boliviana Piper seeds

Canavalia boliviana lectin (Cbol) was purified using a Sephadex G-50 column and crystallized in the presence of X-Man by hanging-drop vapour diffusion at 293 K. After optimization, crystals suitable for diffraction were obtained using 0.1 M HEPES pH 7.5 and 3.0 M sodium formate

Toxicity and Binding Profile of Lectins from the Genus Canavalia on Brine Shrimp

Lectins are sugar-binding proteins widely distributed in nature with many biological functions. Although many lectins have a remarkable biotechnological potential, some of them can be cytotoxic. Thus, the aim of this study was to assess the toxicity of five lectins, purified from seeds of different species of Canavalia genus. In order to determine the toxicity, assays with Artemia nauplii were performed. In addition, a fluorescence assay was carried out to evaluate the binding of lectins to Artemia nauplii. In order to verify the relationship between the structure of lectins and their cytotoxic effect, structural analysis was carried out to evaluate the volume of the carbohydrate recognition domain (CRD) of each lectin. The results showed that all lectins exhibited different toxicities and bound to a similar area in the digestive tract of Artemia nauplii. Concerning the structural analysis, differences in spatial arrangement and volume of CRD may explain the variation of the toxicity exhibited by each lectin. To this date, this is the first study that establishes a link between toxicity and structure of CRD from Diocleinae lectins

A Diocleinae type II lectin from Dioclea lasiophylla Mart. Ex Benth seeds specific to alpha-lactose/GalNAc

A type II lectin, designated as DlyL2, was purified from Dioclea lasiophylla Mart ex Benth seeds and some of its physicochemical properties determined. The lectin demonstrated specificity for alpha-lactose and N-acetyl-D-galactosamine and was able to interact with porcine stomach mucin. DlyL2 has 0.78 % carbohydrates in its composition, therefore can be considered a glycoprotein. In addition, its hemagglutinating activity remained stable M a temperature of 90 degrees C and in a pH range from 5 to 10. Metal chelation treatment did not affect DlyL2 activity suggesting ifs not a metalloprotein. Dly12 showed an apparent mass of 31 kDa and average molecular mass of 26.371 kDa. Primary structure data could be generated from the partial amino acid sequence of DlyL2, with about 192 residues sequenced by a combination of Edman degradation and tandem mass spectrometry. The lectin is similar to other type II lectins from Diocleinae subtribe, as well as lectins derived from species of more ancient tribes of the Fabaceae family. In addition, DlyL2 exhibited no toxicity to Anemia sp. nauplii. The present study expands the knowledge about the specificity, structural and physicochemical properties of Diocleinae type II lectins