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Frutalin (FTL) is a multiple-binding lectin belonging to the jacalin-related lectin (JRL) family and derived from Artocarpus incisa (breadfruit) seeds. This lectin specifically recognizes and binds α-d-galactose. FTL has been successfully used in immunobiological research for the recognition of cancer-associated oligosaccharides. However, the molecular bases by which FTL promotes these specific activities remain poorly understood. Here, we report the whole 3D structure of FTL for the first time, as determined by X-ray crystallography. The obtained crystals diffracted to 1.81 Å (Apo-frutalin) and 1.65 Å (frutalin-d-Gal complex) of resolution. The lectin exhibits post-translational cleavage yielding an α- (133 amino acids) and β-chain (20 amino acids), presenting a homotetramer when in solution, with a typical JRL β-prism. The β-prism was composed of three 4-stranded β-sheets forming three antiparallel Greek key motifs. The carbohydrate-binding site (CBS) involved the N-terminus of the α-chain and was formed by four key residues: Gly25, Tyr146, Trp147 and Asp149. Together, these results were used in molecular dynamics simulations in aqueous solutions to shed light on the molecular basis of FTL-ligand binding. The simulations suggest that Thr-Ser-Ser-Asn (TSSN) peptide excision reduces the rigidity of the FTL CBS, increasing the number of interactions with ligands and resulting in multiple-binding sites and anomeric recognition of α-d-galactose sugar moieties. Our findings provide a new perspective to further elucidate the versatility of FTL in many biological activities., (© 2019 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.)

Main Conclusion: Seeds of native species from the rain forest (Amazon) are source of chitinases and their protein extracts exhibited strong and broad antifungal activity. Numerous plant species native to the Amazon have not yet been chemically studied. Studies of seeds are scarcer, since adversities in accessing study areas and seasonality pose constant hurdles to systematic research. In this study, proteins were extracted from seeds belonging to endemic Amazon species and were investigated for the first time. Proteolytic activity, peptidase inhibitors, and chitinases were identified, but chitinolytic activity predominated. Four proteins were purified through chromatography and identified as lectin and chitinases by MS/MS analyses. The proteins were examined for inhibition of a phytopathogen (Fusarium oxysporum). Analyses by fluorescence microscopy suggested binding of propidium iodide to DNA of fungal spores, revealing that spore integrity was lost when accessed by the proteins. Further structural and functional analyses of defensive proteins belonging to species facing highly complex ecosystems such as Amazonia should be conducted, since these could provide new insights into specificity and synergism involving defense proteins of plants submitted to a very complex ecosystem.

In this study a novel heat-stable lipid transfer protein, designated McLTP1, was purified from noni (Morinda citrifolia L.) seeds, using four purification steps which resulted in a high-purified protein yield (72 mg McLTP1 from 100g of noni seeds). McLTP1 exhibited molecular masses of 9.450 and 9.466 kDa, determined by electrospray ionisation mass spectrometry. The N-terminal sequence of McLTP1 (AVPCGQVSSALSPCMSYLTGGGDDPEARCCAGV), as analysed by NCBI-BLAST database, revealed a high degree of identity with other reported plant lipid transfer proteins. In addition, this protein proved to be resistant to pepsin, trypsin and chymotrypsin digestion. McLTP1 given intraperitoneally (1, 2, 4 and 8 mg/kg) and orally (8 mg/kg) caused an inhibition of the writhing response induced by acetic acid in mice. This protein displayed thermostability, retaining 100% of its antinociceptive activity after 30 min incubation at 80 °C. Pretreatment of mice with McLTP1 (8 mg/kg, i.p. and p.o.) also decreased neurogenic and inflammatory phases of nociception in the formalin test. Naloxone (2 mg/kg, i.p.) antagonised the antinociceptive effect of McLTP1 suggesting that the opioid mechanisms mediate the analgesic properties of this protein., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Nowadays, dengue fever is considered the most important arbovirosis worldwide and its control is still based upon combating the vector Aedes aegypti. Besides monitoring of mosquito populations resistant to conventional insecticides, the search for new environmentally safe insecticides and conduction of molecular studies focusing on the elucidation of mode of action and possible resistance mechanisms are considered the key for a sustainable management of the mosquito vector. Thus, the present work aimed to assess changes in protein expression of 3rd-instar larvae of Ae. aegypti after exposure to the natural insecticide m-pentadecadienyl-phenol. Bidimensional electrophoresis followed by mass spectrometry resulted in identification of 12 proteins differentially expressed between control and treated groups. Larvae exposed to the toxic compound for 24h showed elevated detoxification response (glutathione-S-transferase), increased levels of stress-related proteins (HSP70) as well as evidence of lysosome stabilization to enable survival. Furthermore, expression of proteins involved in protection of peritrophic membrane and metabolism of lipids indicated systemic effect of toxic effects in treated larvae., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Frutalin is an α-D-galactose-specific carbohydrate-binding glycoprotein with antitumour properties and is a powerful tool for tumour biomarker discovery. The crystallization and preliminary X-ray diffraction analysis of this lectin, which was isolated from Artocarpus incisa seeds, are reported here. Frutalin was purified and submitted to mass-spectrometric analysis. Diverse masses at approximately 16 kDa were observed in the deconvoluted spectra, which support the presence of isoforms. The best frutalin crystals were grown within a week in 0.1 M citric acid pH 3.5 which contained 25% PEG 3350 as a precipitant at 293 K, and diffracted to a maximum resolution of 1.81 Å. The monoclinic crystals belonged to space group I2, with unit-cell parameters a = 76.17, b = 74.56, c = 118.98 Å, β = 96.56°. A molecular-replacement solution was obtained which indicated the presence of four monomers per asymmetric unit. Crystallographic refinement of the structure is in progress.

Several studies have described the effects of seed exudates against microorganisms, but only few of them have investigated the proteins that have defensive activity particularly against nematode parasites. This study focused on the proteins released in the exudates of soybean seeds and evaluated their nematicidal properties against Meloidogyne incognita. A proteomic approach indicated the existence of 63 exuded proteins, including β-1,3-glucanase, chitinase, lectin, trypsin inhibitor, and lipoxygenase, all of which are related to plant defense. The presence of some of these proteins was confirmed by their in vitro activity. The soybean exudates were able to reduce the hatching of nematode eggs and to cause 100% mortality of second-stage juveniles (J2). The pretreatment of J2 with these exudates resulted in a 90% reduction of the gall number in tobacco plants. These findings suggest that the exuded proteins are directly involved in plant defense against soil pathogens, including nematodes, during seed germination.

The cashew tree (Anacardium occidentale L.) is a plant native to Brazil and has great commercial value. Among the products marketed from cashew trees, the cashew nut is the most valued, especially for export. However, the presence of allergenic proteins poses a potential threat to those allergic to cashew nuts, but molecular tools including proteomic analysis may be used to allow identification of cashew genotypes with altered allergen content. Here we aimed to identify differentially expressed proteins in common cashew seeds and dwarf FAGA 11 through proteomic analysis. Proteins differentially expressed were excised from two-dimensional gels and analyzed by mass spectrometry (ESI-Q-TOF), then identified using the MASCOT. A total of 18 proteins were analyzed, but only 5 (27%) were not identified. Among the proteins that are unique to common cashew, stand out: the precursor of globulin 11S and Ana 2 protein, both classified as allergenic proteins. The protein Ana o 2 is an 11S globulin and is considered the second most abundant allergen in cashew nuts. Thus, allergenic proteins found in common cashew nuts were observed as expected, but the allergen content of the dwarf FAGA 11 cashew nuts was altered and could represent a new source for biological diversity and allergen content for improved breeding and biotechnological applications. [ABSTRACT FROM AUTHOR]