Mo-CBP3, an antifungal chitin-binding protein from Moringa oleifera seeds, is a member of the 2S albumin family

In-vitro antimicrobial activity of AF-DP protein and in-silico approach of cell membrane disruption

Microbial resistance against common antibiotics has become one of the most serious threats to human health. The increasing statistics on this problem show the necessity of finding a way to deal with it. In recent years, antimicrobial peptides with unique properties and the capability of targeting a wide range of pathogens, have been considered as a potential for replacing common antibiotics. A small chitin-binding protein with anticandidal activity was isolated from Moringa oleifera seeds by Neto and colleagues in 2017, which very much resembled antimicrobial peptides. In this study, the antimicrobial protein 'AF-DP' was identified and characterized. AF-DP was heterologously expressed, purified, and characterized, and its 3D structure was predicted. Six molecular dynamic simulations were performed to investigate how the protein interacts with Gram-negative inner and outer, Gram-positive, fungal, cancerous, and normal mammalian membranes. Also, its antimicrobial and anticancer activity was assessed in vitro via minimum inhibition concentration (MIC) and MTT assays, respectively. This protein with 111 amino acids and a total net charge (of 10.5) has been predicted to be mainly composed of alpha helix and random coils. Its MIC affecting the growth of Escherichia coli, Staphylococcus aureus, and Candida albicans was 30 µg/ml, 100 µg/ml, and 100 µg/ml, respectively; AF-DP showed anticancer activity against MCF-7 breast cancer cell line. Scanning electron microscopic analysis confirmed the creation of pores and scratches on the surface of the bacterial membrane. The results of this research show that AF-DP can be a candidate for the production of new drugs as an AMP with antimicrobial activity.Communicated by Ramaswamy H. Sarma.

Characterization of proteinous coagulant in Moringa tree seeds for water purification: Stepwise laboratory exercise for high-school students

Coagulation is an important process in the context of water purification; and the seed protein of the moringa tree (Moringa oleifera) is a remarkably effective coagulant. The laboratory course described here is designed to provide high-school students with a stepwise, hands-on experience in investigating the protein-rich coagulant found in Moringa seeds. First, the seed powder was applied to model polluted water containing fine clay, food dyes, copper sulfate, and bacteria. This treatment changed the polluted water into clear water via coagulation; all students were convinced that the coagulation-inducing agent was a thermostable cationic protein. Finally, basic biochemical techniques (e.g., chromatographic separation and electrophoresis) were used to show that the target coagulant is a dimeric protein composed of 6.5 and 4.5 kDa subunits. Overall, this made it possible for the students to gain a deeper understanding (more comprehensive than the information taught in formal classes) of protein structure and its real-world implications. This stepwise exercise can be applied to research-based learning programs in high school, as it is an effective learning tool.

Analysis of functional ingredients of tempe-like fermented Moringa oleifera seeds (Moringa tempe) prepared with Rhizopus species

Tempe is a fermented food prepared by fermenting soybeans with Rhizopus species. However, there have recently been concerns about the stable supply of raw soybeans due to global warming and other factors. Moringa is a plant whose cultivation area is expected to expand in the future, and its seeds contain abundant proteins and lipids, and thus could be used as an alternative to soybeans. To develop a novel functional Moringa food, we fermented dehulled Moringa seeds with Rhizopus oligosporus and Rhizopus stolonifer using the solid fermentation method of tempe and investigated changes in the functional components, such as free amino acids and polyphenols, of the respective obtained Moringa tempe Rm and Rs. After 45 h of fermentation, the total content of free amino acids, mainly including gamma-aminobutyric acid and l-glutamic acid, in Moringa tempe Rm was about three times higher, while that in Moringa tempe Rs was almost the same, compared to that in unfermented Moringa seeds. Moreover, after 70 h of fermentation, both Moringa tempe Rm and Rs had approximately four times higher polyphenol content and significantly higher antioxidant activity than did unfermented Moringa seeds. Further, the content of each residual chitin-binding protein of defatted Moringa tempe Rm and Rs was almost the same as that of unfermented Moringa seeds. Taken together, Moringa tempe was rich in free amino acids and polyphenols, exhibited better antioxidant activity, and retained the levels of its chitin-binding proteins, suggesting that Moringa seeds could be used as an alternative to soybean for tempe preparation.

Protein from Hylocereus polyrhizus protects MRC-5 cells against hydrogen peroxide (H2O2)-induced damage

The cytoprotective and potential molecular mechanisms of Hylocereus polyrhizus protein (RFPP) were investigated on the hydrogen peroxide (H2O2)-triggered damage in normal human embryonic lung (MRC-5) cells. An MTT assay was conducted to assess the MRC-5 cell viability after exposure to H2O2 or RFPP. Cell cycle distribution and apoptosis were explored via flow cytometry. The contents of related proteins were assessed via western blot. MRC-5 cells exhibited markedly decreased cellular viability after treatment with H2O2; however, treatment with RFPP suppressed this decrease. Additionally, RFPP interference dampened H2O2-triggered intracellular apoptosis levels and increased H2O2-triggered intracellular S phase. In these processes, the contents of phosphorylated (p)-AKT along with p-mTOR proteins were downregulated in 120 µM H2O2-treated cells compared with vehicle-treated cells. Nevertheless, in MRC-5 cells inoculated with RFPP, the levels expression of these proteins were reversed. To conclude, RFPP protected MRC-5 cells from H2O2-triggered damage via activation of the PI3K/AKT/mTOR cascade.

A new lectin from the floral capitula of Egletes viscosa (EgviL): Biochemical and biophysical characterization and cytotoxicity to human cancer cells

Egletes viscosa is a plant with therapeutic value due to its antibacterial, antinociceptive and gastroprotective properties. This study aimed to purify, characterize, and evaluate the cytotoxicity of a lectin (EgviL) from the floral capitula of E. viscosa. The lectin was isolated from saline extract through precipitation with ammonium sulfate followed by Sephadex G-75 chromatography. The molecular mass and isoelectric point (pI) of EgviL were determined as well as its temperature and pH stability. Physical-chemical parameters of interaction between EgviL and carbohydrates were investigated by fluorescence quenching and ¹H nuclear magnetic resonance (NMR). Cytotoxicity was investigated against human peripheral blood mononuclear cells (PBMCs) and neoplastic cells. EgviL (28.8 kDa, pI 5.4) showed hemagglutinating activity stable towards heating until 60 °C and at the pH range 5.0-7.0. This lectin is able to interact through hydrophobic and electrostatic bonds with galactose and glucose, respectively. EgviL reduced the viability of PBMCs only at the highest concentration tested (100 μg/mL) while was toxic to Jurkat E6-1 cells with IC₅₀ of 24.1 μg/mL,inducing apoptosis. In summary, EgviL is a galactose/glucose-binding protein with acidic character, stable to heating and with cytotoxic effect on leukemic cells.

Identification, characterization and epitope mapping of proteins encoded by putative allergenic napin genes from Brassica rapa

BACKGROUND

Brassica rapeseed crops contain high concentrations of oil in the seed. The remaining meal, following oil extraction, has a high protein content, but is of low value due to the presence of high amounts of napin seed storage proteins. These 2S albumin-like proteins are difficult to digest and have been identified as major allergens in humans.

OBJECTIVE

To comprehensively characterize the napin gene (NG) family in Brassica rapa and to gain an understanding of the structural basis of allergenicity of the expressed proteins.

METHODS

To identify candidate napin genes in B rapa, 2S albumin-like napin genes of Arabidopsis thaliana were used as query sequences to search for similarity against the B rapa var. pekinensis Chiifu-401 v2 and the var. trilocularis R-o-18 v1.5 genomes. Multiple sequence alignment (MSA) and epitope modelling was carried out to determine structural and evolutionary relationships of NGs and their potential allergenicity.

RESULTS

Four candidate napin genes in R-o-18 and ten in Chiifu-401 were identified with high sequence similarity to A thaliana napin genes. Multiple sequence alignment revealed strong conservation among the candidate genes. An epitope survey indicated high conservation of allergenic epitope motifs with known 2S albumin-like allergens.

CONCLUSION

Napin is thought to be responsible for a  high prevalence of food allergies. Characterization of the napin gene family in B rapa will give important insight into the protein structure, and epitope modelling will help to advance studies into allergenicity including the development of precise diagnostic screenings and therapies for this potential food allergy as well as the possible manipulation of napin levels in the seed by gene editing technology.

Mo-HLPs: New flocculating agents identified from Moringa oleifera seeds belong to the hevein-like peptide family

Cationic peptides found in Moringa oleifera seeds belong to different protein families and are described as the main flocculating agents of the species. In this study we report the identification and isolation of four new flocculant peptides, called Mo-HLPs 1-4, belonging to the family of hevein-like peptides, previously only known for their members' antimicrobial activity. Purification of the peptides followed two sequential membrane ultrafiltration steps and separation by reverse-phase liquid chromatography. Proteomic analyses showed that Mo-HLPs are extremely basic (pI >10) cysteine-rich molecules with molecular masses between 4.5 and 4.8 kDa and with a highly conserved chitin-binding domain. Searches in BLAST revealed high similarity of Mo-HLPs with hevein and other hevein-like peptides and 90% identity with morintides, which are members of the 8C-hevein-like subfamily found in M. oleifera leaves. Mo-HLPs microflocculation assays showed distinct coagulation/flocculation efficiencies, promoting turbidity reduction levels between 67 and 89% in synthetic turbid water. Activity variations were attributed to the substitution of some amino acids among the isoforms, which may have altered the final net charge of the molecules. The identification of Mo-HLPs represents the discovery of a new group of cationic peptides involved in the flocculation properties of M. oleifera seeds. SIGNIFICANCE: The study reveals the presence of hevein-like peptides in Moringa oleifera seeds. It is reported for the first time that members of this family have properties to act as flocculating agents of importance for water treatment processes. The identification of these peptides as well as new functional assignment broadens the horizon for speculation on new species which could act as sources of green coagulants for sustainable water treatment, and contributes to the knowledge about occurrence, distribution, molecular and active diversity of peptides belonging to the hevein-like family.

Application of Moringa oleifera Lam. fractionated proteins for inactivation of Escherichia coli from water

Chemical products traditionally used in the disinfection of water bodies often pose human health risks. For this reason, studies on natural coagulants such as Moringa oleifera Lam. represent an alternative for the inactivation of pathogenic microorganisms, among which is Escherichia coli. This study evaluated the effect of different concentrations of coagulants obtained from Moringa seed extracts and their protein fractions in the inactivation of E. coli during the coagulation/flocculation process. The coagulants studied were the aqueous extract, saline extract and protein fractions albumin and globulin, highlighting that the protein fractions were more effective on inactivating E. coli. The protein fraction globulin at a concentration of 10.0 mg L^-1 showed bactericidal effects against E. coli within 18 min, whereas the albumin showed a bacteriostatic effect within 48 min because it isolated colonies in the sediment sample.

Comparative study of flocculation and adsorption behaviour of water treatment proteins from Moringa peregrina and Moringa oleifera seeds

Trees of Moringa oleifera are the most widely exploited species of Moringa and proteins extracted from its seeds have been identified as the most efficient natural coagulant for water purification. Largely for climatic reasons, other Moringa species are more accessible in some regions and this paper presents a comparative study of the adsorption to different materials of the proteins extracted from seeds of Moringa peregrina and Moringa oleifera to explore their use as flocculating agents in regions where each is more readily accessible. Results showed that Moringa peregrina seed proteins had higher adsorption to alumina compared to silica, in contrast to opposite behavior for Moringa oleifera. Both species provide cationic proteins that can act as effective coagulants for the various impurities with different surface potential. Despite the considerable similarity of the amino acid composition, the seed proteins have significantly different adsorption and this presents the opportunity to improve processes by choosing the optimal species or combination of species depending on the type of impurity or possible development of separation processes.

7 Log Virus Removal in a Simple Functionalized Sand Filter

Viral contamination of drinking water due to fecal contamination is difficult to detect and treat effectively, leading to frequent outbreaks worldwide. The purpose of this paper is to report on the molecular mechanism for unprecedented high virus removal from a practical sand filter. Sand filters functionalized using a water extract of Moringa oleifera (MO) seeds, functionalized sand (f-sand) filters, achieved a ∼7 log₁₀ virus removal. These tests were conducted with MS2 bacteriophage, a recognized surrogate for pathogenic norovirus and rotavirus. We studied the molecular mechanism of this high removal since it can have important implications for sand filtration, the most common water treatment technology worldwide. Our data reveal that the virus removal activity of f-sand is due to the presence of a chitin-binding protein, M. oleifera chitin-binding protein (MoCBP) on f-sand. Standard column experiments were supported by proteomic analysis and molecular docking simulations. Our simulations show that MoCBP binds preferentially to MS2 capsid proteins demonstrating that specific molecular interactions are responsible for enhanced virus removal. In addition, we simplified the process of making f-sand and evinced how it could be regenerated using saline water. At present, no definitive solution exists for the challenge of treating fecally contaminated drinking and irrigation water for viruses without using technologies that demand high energy or chemical consumption. We propose functionalized sand (f-sand) filters as a highly effective, energy-efficient, and practical technology for virus removal applicable to both developing and developed countries.

Biological, nutritional, and therapeutic significance of Moringa oleifera Lam

The genus Moringa Adans. comprises 13 species, of which Moringa oleifera Lam. native to India and cultivated across the world owing to its drought and frost resistance habit is widely used in traditional phytomedicine and as rich source of essential nutrients. Wide spectrum of phytochemical ingredients among leaf, flower, fruit, seed, seed oil, bark, and root depend on cultivar, season, and locality. The scientific studies provide insights on the use of M. oleifera with different aqueous, hydroalcoholic, alcoholic, and other organic solvent preparations of different parts for therapeutic activities, that is, antibiocidal, antitumor, antioxidant, anti-inflammatory, cardio-protective, hepato-protective, neuro-protective, tissue-protective, and other biological activities with a high degree of safety. A wide variety of alkaloid and sterol, polyphenols and phenolic acids, fatty acids, flavanoids and flavanol glycosides, glucosinolate and isothiocyanate, terpene, anthocyanins etc. are believed to be responsible for the pragmatic effects. Seeds are used with a view of low-cost biosorbent and coagulant agent for the removal of metals and microbial contamination from waste water. Thus, the present review explores the use of M. oleifera across disciplines for its prominent bioactive ingredients, nutraceutical, therapeutic uses and deals with agricultural, veterinarian, biosorbent, coagulation, biodiesel, and other industrial properties of this "Miracle Tree."

Using Moringa oleifera Lamarck seed extract for controlling microbial contamination when producing organic cachaça

This study investigated the use of seed extract from Moringa oleifera Lamark (MO) for both clarifying the sugarcane juice and removing fermentation contaminants that originated during the 24 h storage of the freshly cut stalks. The addition of the MO seed extract during the juice clarification step decreased the total microbial population by 41.66% compared to the other treatments. The non-stored raw material had less lactic acid bacteria and yeasts counts in the fermentation process, resulting in 8.8% lower glycerol content compared to the stored raw material. The concentrations of congeners in both raw materials decreased by 5.27% after liming and by 10% after using the natural extract with flocculation activity. It can be concluded that the clarification process combined with the use of the seed extract from Moringa oleifera Lamarck can potentially control microbial contaminating during fermentation and increase the alcohol content in the cachaça.

Antifungal Proteins with Antiproliferative Activity on Cancer Cells and HIV-1 Enzyme Inhibitory Activity from Medicinal Plants and Medicinal Fungi

A variety of fungi, plants, and their different tissues are used in Traditional Chinese Medicine to improve health, and some of them are recommended for dietary therapy. Many of these plants and fungi contain antifungal proteins and peptides which suppress spore germination and hyphal growth in phytopathogenic fungi. The aim of this article is to review antifungal proteins produced by medicinal plants and fungi used in Chinese medicine which also possess anticancer and human immunodeficiency virus-1 (HIV-1) enzyme inhibitory activities.

Mo-CBP3, a 2S albumin from Moringa oleifera, is a complex mixture of isoforms that arise from different post-translational modifications

Mo-CBP₃ is a chitin-binding 2S albumin from Moringa oleifera. This seed storage protein is resistant to thermal denaturation and shows biological activities that might be of practical use, such as antifungal properties against Candida sp., a pathogen that causes candidiasis, and against Fusarium solani, a soil fungus that can cause diseases in plants and humans. Previous work has demonstrated that Mo-CBP₃ is a mixture of isoforms encoded by members of a small multigene family. Mature Mo-CBP3 is a small protein (∼14 kDa), constituted by a small chain of approximately 4 kDa and a large chain of 8 kDa, which are held together by disulfide bridges. However, a more comprehensive picture on the spectrum of Mo-CBP₃ isoforms which are found in mature seeds, is still lacking. In this work, genomic DNA fragments were obtained from M. oleifera leaves, cloned and completely sequenced, thus revealing new genes encoding Mo-CBP₃. Moreover, mass spectrometry analysis showed that the mature protein is a complex mixture of isoforms with a remarkable number of molecular mass variants. Using computational predictions and calculations, most (∼86%) of the experimentally determined masses were assigned to amino acid sequences deduced from DNA fragments. The results suggested that the complex mixture of Mo-CBP₃ isoforms originates from proteins encoded by closely related genes, whose products undergo different combinations of distinct post-translational modifications, including cleavage at the N- and C-terminal ends of both subunits, cyclization of N-terminal Gln, as well as Pro hydroxylation, Ser/Thr phosphorylation, and Met oxidation.

Gene expression and spatiotemporal localization of antifungal chitin-binding proteins during Moringa oleifera seed development and germination

Chitin-binding proteins behave as storage and antifungal proteins in the seeds of Moringa oleifera. Moringa oleifera is a tropical multipurpose tree. Its seed constituents possess coagulant, bactericidal, fungicidal, and insecticidal properties. Some of these properties are attributed to a group of polypeptides denominated M. oleifera chitin-binding proteins (in short, Mo-CBPs). Within this group, Mo-CBP₂, Mo-CBP₃, and Mo-CBP₄ were previously purified to homogeneity. They showed high amino acid similarity with the 2S albumin storage proteins. These proteins also presented antimicrobial activity against human pathogenic yeast and phytopathogenic fungi. In the present study, the localization and expression of genes that encode Mo-CBPs and the biosynthesis and degradation of the corresponding proteins during morphogenesis and maturation of M. oleifera seeds at 15, 30, 60, and 90 days after anthesis (DAA) and germination, respectively, were assessed. The Mo-CBP transcripts and corresponding proteins were not detected at 15 and 30 days after anthesis (DAA). However, they accumulated at the latter stages of seed maturation (60 and 90 DAA), reaching the maximum level at 60 DAA. The degradation kinetics of Mo-CBPs during seed germination by in situ immunolocalization revealed a reduction in the protein content 48 h after sowing (HAS). Moreover, Mo-CBPs isolated from seeds at 60 and 90 DAA prevented the spore germination of Fusarium spp. Taken together, these results suggest that Mo-CBPs play a dual role as storage and defense proteins in the seeds of M. oleifera.

A review of phytochemistry, metabolite changes, and medicinal uses of the common sunflower seed and sprouts (Helianthus annuus L.)

The sunflower (Helianthus annuus L.) seed and sprout is a ubiquitous crop with abundant nutrients and biological activities. This review summarizes the nutritional and medical importance currently recognized but under-researched concerning both seed and sprout highlighting the potential benefits of their phytochemical constituents including phenolic acids, flavonoids and tocopherols. Furthermore, the dynamic metabolite changes which occur during germination and biological activities are evaluated. The aim is to provide scientific evidence for improving the dietary and pharmaceutical applications of this common but popular crop as a functional food.

A Chitin-binding Protein Purified from Moringa oleifera Seeds Presents Anticandidal Activity by Increasing Cell Membrane Permeability and Reactive Oxygen Species Production

Candida species are opportunistic pathogens that infect immunocompromised and/or immunosuppressed patients, particularly in hospital facilities, that besides representing a significant threat to health increase the risk of mortality. Apart from echinocandins and triazoles, which are well tolerated, most of the antifungal drugs used for candidiasis treatment can cause side effects and lead to the development of resistant strains. A promising alternative to the conventional treatments is the use of plant proteins. M. oleifera Lam. is a plant with valuable medicinal properties, including antimicrobial activity. This work aimed to purify a chitin-binding protein from M. oleifera seeds and to evaluate its antifungal properties against Candida species. The purified protein, named Mo-CBP₂, represented about 0.2% of the total seed protein and appeared as a single band on native PAGE. By mass spectrometry, Mo-CBP₂ presented 13,309 Da. However, by SDS-PAGE, Mo-CBP₂ migrated as a single band with an apparent molecular mass of 23,400 Da. Tricine-SDS-PAGE of Mo-CBP₂ under reduced conditions revealed two protein bands with apparent molecular masses of 7,900 and 4,600 Da. Altogether, these results suggest that Mo-CBP₂ exists in different oligomeric forms. Moreover, Mo-CBP₂ is a basic glycoprotein (pI 10.9) with 4.1% (m/m) sugar and it did not display hemagglutinating and hemolytic activities upon rabbit and human erythrocytes. A comparative analysis of the sequence of triptic peptides from Mo-CBP₂ in solution, after LC-ESI-MS/MS, revealed similarity with other M. oleifera proteins, as the 2S albumin Mo-CBP₃ and flocculating proteins, and 2S albumins from different species. Mo-CBP₂ possesses in vitro antifungal activity against Candida albicans, C. parapsilosis, C. krusei, and C. tropicalis, with MIC₅₀ and MIC₉₀ values ranging between 9.45–37.90 and 155.84–260.29 μM, respectively. In addition, Mo-CBP₂ (18.90 μM) increased the cell membrane permeabilization and reactive oxygen species production in C. albicans and promoted degradation of circular plasmid DNA (pUC18) from Escherichia coli. The data presented in this study highlight the potential use of Mo-CBP₂ as an anticandidal agent, based on its ability to inhibit Candida spp. growth with apparently low toxicity on mammalian cells.

Proteomic Profiles Reveal the Function of Different Vegetative Tissues of Moringa oleifera

Moringa oleifera is a rich source of bioactive compounds and is widely used in traditional medicine and food for its nutritional value; however, the protein and peptide components of different tissues are rarely discussed. Here, we describe the first investigation of M. oleifera proteomes using mass spectrometry and bioinformatics methods. We aimed to elucidate the protein profiles of M. oleifera leaves, stem, bark, and root. Totally 202 proteins were identified from four vegetative organs. We identified 101 proteins from leaves, 51 from stem, 94 from bark and 67 from root, finding that only five proteins existed in both four vegetative parts. The calculated pI of most of the proteins is distributed in 5-10 and the molecular weight distributed below 100 kDa. Functional classification analysis revealed that proteins which are involved in catalytic activities are the most abundant both in leaves, stem, bark and root. Identification of several heat shock proteins in four vegetative tissues might be adaptive for resistance to high temperature environmental stresses of tropical or subtropical areas. Some enzymes involved in antioxidant processes were also identified in M. oleifera leaves, stem, bark and root. Among the four tissues studies here, leaves protein content and molecular diversity were the highest. The identification of the flocculating protein MO2.1 and MO2.2 in the bark and root provides clue to clarify the antimicrobial molecular mechanisms of root and bark. This study provides information on the protein compositions of M. oleifera vegetative tissues that will be beneficial for potential drug and food supplement development and plant physiology research.

Phytochemicals of Moringa oleifera: a review of their nutritional, therapeutic and industrial significance

Moringa oleifera Lam., also known as the ‘drumstick tree,’ is recognized as a vibrant and affordable source of phytochemicals, having potential applications in medicines, functional food preparations, water purification, and biodiesel production. The multiple biological activities including antiproliferation, hepatoprotective, anti-inflammatory, antinociceptive, antiatherosclerotic, oxidative DNA damage protective, antiperoxidative, cardioprotective, as well as folk medicinal uses of M. oleifera (MO) are attributed to the presence of functional bioactive compounds, such as phenolic acids, flavonoids, alkaloids, phytosterols, natural sugars, vitamins, minerals, and organic acids. The low molecular weight of M. oleifera cationic proteins (MOCP) extracted from the seeds is very useful and is used in water purification, because of its potent antimicrobial and coagulant properties. Also, the M. oleifera methyl esters (MOME) produced from the oil of the seeds meet the major specifications of the biodiesel standard of Germany, Europe, and United States (US). Thus, MO is emerging as one of the prominent industrial crops for sustainable biodiesel production in tropical and subtropical countries. In view of the high nutritional, nutraceutical, and industrial values, it is important to compile an updated comprehensive review on the related aspects of this multipurpose and miracle tree. Hence, the present study is focused on the nutritionally significant bioactives and medicinal and biological properties, to explore the potential applications of MO in nutritionally rich food preparations. Furthermore, water coagulation, proteins, and fatty acid methyl esters from the MO seeds are reviewed, to explore their possible industrial applications in biodiesel production and water purification. In addition, the future perspectives in these areas are suggested.

A tripartite approach identifies the major sunflower seed albumins

We have used a combination of genomic, transcriptomic, and proteomic approaches to identify the napin-type albumin genes in sunflower and define their contributions to the seed albumin pool. Seed protein content is determined by the expression of what are typically large gene families. A major class of seed storage proteins is the napin-type, water soluble albumins. In this work we provide a comprehensive analysis of the napin-type albumin content of the common sunflower (Helianthus annuus) by analyzing a draft genome, a transcriptome and performing a proteomic analysis of the seed albumin fraction. We show that although sunflower contains at least 26 genes for napin-type albumins, only 15 of these are present at the mRNA level. We found protein evidence for 11 of these but the albumin content of mature seeds is dominated by the encoded products of just three genes. So despite high genetic redundancy for albumins, only a small sub-set of this gene family contributes to total seed albumin content. The three genes identified as producing the majority of sunflower seed albumin are potential future candidates for manipulation through genetics and breeding.

Crystal structure of mature 2S albumin from Moringa oleifera seeds

2S albumins, the seed storage proteins, are the primary sources of carbon and nitrogen and are involved in plant defense. The mature form of Moringa oleifera (M. oleifera), a chitin binding protein isoform 3-1 (mMo-CBP3-1) a thermostable antifungal, antibacterial, flocculating 2S albumin is widely used for the treatment of water and is potentially interesting for the development of both antifungal drugs and transgenic crops. The crystal structure of mMo-CBP3-1 determined at 1.7 Å resolution demonstrated that it is comprised of two proteolytically processed α-helical chains, stabilized by four disulfide bridges that is stable, resistant to pH changes and has a melting temperature (TM) of approximately 98 °C. The surface arginines and the polyglutamine motif are the key structural factors for the observed flocculating, antibacterial and antifungal activities. This represents the first crystal structure of a 2S albumin and the model of the pro-protein indicates the structural changes that occur upon formation of mMo-CBP3-1 and determines the structural motif and charge distribution patterns for the diverse observed activities.

Food safety assessment of an antifungal protein from Moringa oleifera seeds in an agricultural biotechnology perspective

Mo-CBP3 is an antifungal protein produced by Moringa oleifera which has been investigated as potential candidate for developing transgenic crops. Before the use of novel proteins, food safety tests must be conducted. This work represents an early food safety assessment of Mo-CBP3, using the two-tiered approach proposed by ILSI. The history of safe use, mode of action and results for amino acid sequence homology using the full-length and short contiguous amino acids sequences indicate low risk associated to this protein. Mo-CBP3 isoforms presented a reasonable number of alignments (>35% identity) with allergens in a window of 80 amino acids. This protein was resistant to pepsin degradation up to 2 h, but it was susceptible to digestion using pancreatin. Many positive attributes were presented for Mo-CBP3. However, this protein showed high sequence homology with allergens and resistance to pepsin digestion that indicates that further hypothesis-based testing on its potential allergenicity must be done. Additionally, animal toxicity evaluations (e.g. acute and repeated dose oral exposure assays) must be performed to meet the mandatory requirements of several regulatory agencies. Finally, the approach adopted here exemplified the importance of performing an early risk assessment of candidate proteins for use in plant transformation programs.