Structural and bioinformatic analysis of the kiwifruit allergen Act d 11, a member of the family of ripening-related proteins

Characterisation of the MLP genes in peach postharvest cold storage and the regulatory role of PpMLP10 in the chilling stress response

The major latex proteins/ripening-related proteins are a subfamily of the Bet v 1 protein superfamily and are commonly involved in plant development and responses to various stresses. However, the functions of MLPs in the postharvest cold storage of fruits remain uninvestigated. Herein, we identified 30 MLP genes in the peach (Prunus persica) genome that were clustered into three subgroups. Chromosomal location analysis revealed that the PpMLP genes were unevenly distributed on five of the eight peach chromosomes. Synteny analysis of the MLP genes between peach and seven other plant species (five dicotyledons and two monocotyledons) explored their evolutionary characteristics. Furthermore, the PpMLP promoters contained cis-elements for multiple hormones and stress responses. Gene expression analysis revealed that PpMLPs participated in chilling stress responses. Ectopic expression of PpMLP10 in Arabidopsis improved chilling stress tolerance by decreasing membrane damage and maintaining membrane stability. Additional research confirmed that PpWRKY2 participates in PpMLP10-mediated chilling stress by binding to its promoter. Collectively, these results suggest the role of PpMLP10 in enhancing chilling stress tolerance, which is significant for decreasing chilling injury during the postharvest cold storage of peaches.

Identification of a 17 kDa protein that is a potentially novel antigen of lettuce-associated respiratory allergy in farmers

BACKGROUND

We have identified and reported a novel antigen, nonprotein-specific secreted EP1-like glycoprotein (51 kDa), for lettuce-related respiratory allergy.

OBJECTIVE

We aimed to identify a novel antigen for lettuce-related respiratory allergy that is different from epidermis-specific secreted EP1-like glycoprotein.

METHODS

Immunoblotting was performed using an immunoglobulin E-specific antibody. The antigen-antibody reaction was confirmed by means of enzyme-linked immunosorbent assaying. LC-MS/MS analysis was carried out to detect a novel protein found in sera from 3 of 13 patients with lettuce-related respiratory allergy. Finally, we purified a novel protein from Escherichia coli.

RESULTS

Immunoblotting assays showed common bands of 17 kDa in the sera of 3 of 13 patients. An enzyme-linked immunosorbent assay confirmed that the patient sera reacted with lettuce latex juice. A 17 kDa protein band that showed antigenic reactivity in 3 of 13 patient sera was identified as a kirola-like protein by LC-MS/MS. In addition, although we purified this protein, we failed to show the inhibitory effect.

CONCLUSION

A 17 kDa protein that is a potentially novel antigen of lettuce-associated respiratory allergy was identified. In further studies, we will focus on purifying this novel protein to diagnose lettuce allergy.

Structural Basis of the Immunological Cross-Reactivity between Kiwi and Birch Pollen

Allergies related to kiwi consumption have become a growing health concern, with their prevalence on the rise. Many of these allergic reactions are attributed to cross-reactivity, particularly with the major allergen found in birch pollen. This cross-reactivity is associated with proteins belonging to the pathogenesis-related class 10 (PR-10) protein family. In our study, we determined the three-dimensional structures of the two PR-10 proteins in gold and green kiwi fruits, Act c 8 and Act d 8, using nuclear magnetic resonance (NMR) spectroscopy. The structures of both kiwi proteins closely resemble the major birch pollen allergen, Bet v 1, providing a molecular explanation for the observed immunological cross-reactivity between kiwi and birch pollen. Compared to Act d 11, however, a kiwi allergen that shares the same architecture as PR-10 proteins, structural differences are apparent. Moreover, despite both Act c 8 and Act d 8 containing multiple cysteine residues, no disulfide bridges are present within their structures. Instead, all the cysteines are accessible on the protein's surface and exposed to the surrounding solvent, where they are available for reactions with components of the natural food matrix. This structural characteristic sets Act c 8 and Act d 8 apart from other kiwi proteins with a high cysteine content. Furthermore, we demonstrate that pyrogallol, the most abundant phenolic compound found in kiwi, binds into the internal cavities of these two proteins, albeit with low affinity. Our research offers a foundation for further studies aimed at understanding allergic reactions associated with this fruit and exploring how interactions with the natural food matrix might be employed to enhance food safety.

Genome-Wide Evolutionary Characterization and Expression Analysis of Major Latex Protein (MLP) Family Genes in Tomato

Major latex proteins (MLPs) play a key role in plant response to abiotic and biotic stresses. However, little is known about this gene family in tomatoes (Solanum lycopersicum). In this paper, we perform a genome-wide evolutionary characterization and gene expression analysis of the MLP family in tomatoes. We found a total of 34 SlMLP members in the tomato genome, which are heterogeneously distributed on eight chromosomes. The phylogenetic analysis of the SlMLP family unveiled their evolutionary relationships and possible functions. Furthermore, the tissue-specific expression analysis revealed that the tomato MLP members possess distinct biological functions. Crucially, multiple cis-regulatory elements associated with stress, hormone, light, and growth responses were identified in the promoter regions of these SlMLP genes, suggesting that SlMLPs are potentially involved in plant growth, development, and various stress responses. Subcellular localization demonstrated that SlMLP1, SlMLP3, and SlMLP17 are localized in the cytoplasm. In conclusion, these findings lay a foundation for further dissecting the functions of tomato SlMLP genes and exploring the evolutionary relationships of MLP homologs in different plants.

Role of Small Molecule Ligands in IgE-Mediated Allergy

PURPOSE OF REVIEW

A significant fraction of allergens bind small molecular ligands, and many of these compounds are classified as lipids. However, in most cases, we do not know the role that is played by the ligands in the allergic sensitization or allergic effector phases.

RECENT FINDINGS

More effort is dedicated toward identification of allergens' ligands. This resulted in identification of some lipidic compounds that can play active immunomodulatory roles or impact allergens' molecular and allergic properties. Four allergen families (lipocalins, NPC2, nsLTP, and PR-10) are among the best characterized in terms of their ligand-binding properties. Allergens from these four families are able to bind many chemically diverse molecules. These molecules can directly interact with human immune system and/or affect conformation and stability of allergens. While there is more data on the allergens and their small molecular ligands, we are just starting to understand their role in allergy.

Overexpression of major latex protein 423 (NtMLP423) enhances the chilling stress tolerance in Nicotiana tabacum

Chilling stress impedes plant growth and hinders crop development and productivity. In this study, we identified the major latex protein (MLP) in tobacco (NtMLP423) and examined its roles in chilling resistance. NtMLP423 expression was considerably upregulated in response to chilling stress. NtMLP423 function was assessed and compared in plants with overexpression and antisense characteristics. Under chilling stress, plants with overexpression characteristics grew better than wild-type and antisense plants. NtMLP423 overexpression reduced membrane lipid damage, increased antioxidant enzyme activity, and reduced reactive oxygen species (ROS) accumulation under chilling stress. Here, we screened for the first time the upstream transcription factor NtMYB108, which regulates NtMLP423 expression under chilling stress. The NtMYB108 transcription factor directly binds to the NtMLP423 promoter and improves NtMLP423 resistance to chilling stress. Subjecting NtMYB018 to virus-induced gene silencing reduced chilling stress tolerance. Overall, NtMLP423 overexpression enhances chilling stress tolerance, while its suppression has the opposite effect.

Genome-wide characterization of major latex protein gene family in peanut and expression analyses under drought and waterlogging stress

Peanut is an important oilseed crop around the world which provides vegetable oil, protein and vitamins for humans. Major latex-like proteins (MLPs) play important roles in plant growth and development, as well as responses to biotic and abiotic stresses. However, their biological function in peanut is still unclear. In this study, a genome-wide identification of MLP genes in cultivated peanut and two diploid ancestor species was analyzed to determine their molecular evolutionary characteristics and the expression profile under drought and waterlogging stress conditions. Firstly, a total of 135 MLP genes were identified from the genome of tetraploid peanut (Arachis hypogaea) and two diploid species Arachis. duranensis and Arachis. ipaensis. Then, phylogenetic analysis revealed that MLP proteins were divided into five different evolutionary groups. These genes were distributed unevenly at the ends of chromosomes 3, 5, 7, 8, 9 and 10 in three Arachis species. The evolution of MLP gene family in peanut was conserved and led by tandem and segmental duplication. The prediction analysis of cis-acting elements showed that the promoter region of peanut MLP genes contained different proportions of transcription factors, plant hormones-responsive elements and so on. The expression pattern analysis showed that they were differentially expressed under waterlogging and drought stress. These results of this study provide a foundation for further research on the function of the important MLP genes in peanut.

Functional Studies of Plant Latex as a Rich Source of Bioactive Compounds: Focus on Proteins and Alkaloids

Latex, a sticky emulsion produced by specialized cells called laticifers, is a crucial part of a plant's defense system against herbivory and pathogens. It consists of a broad spectrum of active compounds, which are beneficial not only for plants, but for human health as well, enough to mention the use of morphine or codeine from poppy latex. Here, we reviewed latex's general role in plant physiology and the significance of particular compounds (alkaloids and proteins) to its defense system with the example of Chelidonium majus L. from the poppy family. We further attempt to present latex chemicals used so far in medicine and then focus on functional studies of proteins and other compounds with potential pharmacological activities using modern techniques such as CRISPR/Cas9 gene editing. Despite the centuries-old tradition of using latex-bearing plants in therapies, there are still a lot of promising molecules waiting to be explored.

Combined Protein and Alkaloid Research of Chelidonium majus Latex Reveals CmMLP1 Accompanied by Alkaloids with Cytotoxic Potential to Human Cervical Carcinoma Cells

Chelidonium majus L. is a latex-bearing plant used in traditional folk medicine to treat human papillomavirus (HPV)-caused warts, papillae, and condylomas. Its latex and extracts are rich in many low-molecular compounds and proteins, but there is little or no information on their potential interaction. We describe the isolation and identification of a novel major latex protein (CmMLP1) composed of 147 amino acids and present a model of its structure containing a conserved hydrophobic cavity with high affinity to berberine, 8-hydroxycheleritrine, and dihydroberberine. CmMLP1 and the accompanying three alkaloids were present in the eluted chromatographic fractions of latex. They decreased in vitro viability of human cervical cancer cells (HPV-negative and HPV-positive). We combined, for the first time, research on macromolecular and low-molecular-weight compounds of latex-bearing plants in contrast to other studies that investigated proteins and alkaloids separately. The observed interaction between latex protein and alkaloids may influence our knowledge on plant defense. The proposed toolbox may help in further understanding of plant disease resistance and in pharmacological research.

Transport enhancement of hydrophobic pollutants by the expression of zucchini major latex-like protein genes in tobacco plants

The environmental spread of hydrophobic pollutants has been receiving attention because of specific characteristics of these compounds that make them resistant to degradation, thus causing various toxic effects on humans as a result of their bioaccumulation. Here, we report the role of zucchini major-latex like proteins (MLPs) on the accumulation of hydrophobic pollutants, as consumption of contaminated crops is one of the main routes for accumulation. Transgenic tobacco plants expressing an aryl hydrocarbon receptor (AhR) gene with a β-glucuronidase (GUS) inducible expression system were transformed with one of the three zucchini MLP genes (PG1, GR1, and GR3). MLP transgenic plants showed a significant increase in the fold induction of GUS activity compared to the parental AhR tobacco plants when one of the most toxic polychlorinated biphenyl (PCB) congeners, 3,3',4,4',5-pentachlorobiphenyl (CB126), was applied. GUS activity was detected in both aerial parts and roots after treatment with the strong carcinogen 3-methylcholanthrene. Phenotypic changes in the MLP tobacco during incubation with CB126 were also observed. The MLP transgenic plant PG1 responded to treatment with 0.32 nM CB126, whereas vector control plants significantly induced GUS activity at 200 nM CB126. Moreover, GUS activities in the MLP plants treated with other PCB congeners were significantly higher than those in the plants given the mock treatment. As GUS activities in the aerial parts of the plants were significantly correlated with the accumulation level of PCBs, these results strongly suggest that zucchini MLPs are related to the translocation of hydrophobic pollutants from the roots to the aerial parts through their binding affinity.

Allergens and their associated small molecule ligands-their dual role in sensitization

Many allergens feature hydrophobic cavities that allow the binding of primarily hydrophobic small‐molecule ligands. Ligand‐binding specificities can be strict or promiscuous. Serum albumins from mammals and birds can assume multiple conformations that facilitate the binding of a broad spectrum of compounds. Pollen and plant food allergens of the family 10 of pathogenesis‐related proteins bind a variety of small molecules such as glycosylated flavonoid derivatives, flavonoids, cytokinins, and steroids in vitro. However, their natural ligand binding was reported to be highly specific. Insect and mammalian lipocalins transport odorants, pheromones, catecholamines, and fatty acids with a similar level of specificity, while the food allergen β‐lactoglobulin from cow's milk is notably more promiscuous. Non‐specific lipid transfer proteins from pollen and plant foods bind a wide variety of lipids, from phospholipids to fatty acids, as well as sterols and prostaglandin B2, aided by the high plasticity and flexibility displayed by their lipid‐binding cavities. Ligands increase the stability of allergens to thermal and/or proteolytic degradation. They can also act as immunomodulatory agents that favor a Th2 polarization. In summary, ligand‐binding allergens expose the immune system to a variety of biologically active compounds whose impact on the sensitization process has not been well studied thus far.

Structural Characterization of Act c 10.0101 and Pun g 1.0101-Allergens from the Non-Specific Lipid Transfer Protein Family

(1) Background: Non-specific lipid transfer proteins (nsLTPs), which belong to the prolamin superfamily, are potent allergens. While the biological role of LTPs is still not well understood, it is known that these proteins bind lipids. Allergen nsLTPs are characterized by significant stability and resistance to digestion. (2) Methods: nsLTPs from gold kiwifruit (Act c 10.0101) and pomegranate (Pun g 1.0101) were isolated from their natural sources and structurally characterized using X-ray crystallography (3) Results: Both proteins crystallized and their crystal structures were determined. The proteins have a very similar overall fold with characteristic compact, mainly α-helical structures. The C-terminal sequence of Act c 10.0101 was updated based on our structural and mass spectrometry analysis. Information on proteins’ sequences and structures was used to estimate the risk of cross-reactive reactions between Act c 10.0101 or Pun g 1.0101 and other allergens from this family of proteins. (4) Conclusions: Structural studies indicate a conformational flexibility of allergens from the nsLTP family and suggest that immunoglobulin E binding to some surface regions of these allergens may depend on ligand binding. Both Act c 10.0101 and Pun g 1.0101 are likely to be involved in cross-reactive reactions involving other proteins from the nsLTP family.

Proteome changes in pepper (Capsicum annuum L.) leaves induced by the green peach aphid (Myzus persicae Sulzer)

BACKGROUND

Aphid attack induces defense responses in plants activating several signaling cascades that led to the production of toxic, repellent or antinutritive compounds and the consequent reorganization of the plant primary metabolism. Pepper (Capsicum annuum L.) leaf proteomic response against Myzus persicae (Sulzer) has been investigated and analyzed by LC-MS/MS coupled with bioinformatics tools.

RESULTS

Infestation with an initially low density (20 aphids/plant) of aphids restricted to a single leaf taking advantage of clip cages resulted in 6 differentially expressed proteins relative to control leaves (3 proteins at 2 days post-infestation and 3 proteins at 4 days post-infestation). Conversely, when plants were infested with a high density of infestation (200 aphids/plant) 140 proteins resulted differentially expressed relative to control leaves (97 proteins at 2 days post-infestation, 112 proteins at 4 days post-infestation and 105 proteins at 7 days post-infestation). The majority of proteins altered by aphid attack were involved in photosynthesis and photorespiration, oxidative stress, translation, protein folding and degradation and amino acid metabolism. Other proteins identified were involved in lipid, carbohydrate and hormone metabolism, transcription, transport, energy production and cell organization. However proteins directly involved in defense were scarce and were mostly downregulated in response to aphids.

CONCLUSIONS

The unexpectedly very low number of regulated proteins found in the experiment with a low aphid density suggests an active mitigation of plant defensive response by aphids or alternatively an aphid strategy to remain undetected by the plant. Under a high density of aphids, pepper leaf proteome however changed significantly revealing nearly all routes of plant primary metabolism being altered. Photosynthesis was so far the process with the highest number of proteins being regulated by the presence of aphids. In general, at short times of infestation (2 days) most of the altered proteins were upregulated. However, at longer times of infestation (7 days) the protein downregulation prevailed. Proteins involved in plant defense and in hormone signaling were scarce and mostly downregulated.

Pesticide treatment reduces hydrophobic pollutant contamination in Cucurbita pepo through competitive binding to major latex-like proteins

Hydrophobic pollutants are still present in agricultural soil. The Cucurbitaceae family accumulates hydrophobic pollutants through roots, resulting in the contamination of aerial parts. Major latex-like proteins (MLPs), found in the Cucurbitaceae family, play an important role in the contamination by binding to these hydrophobic pollutants. Thus far, efficient cultivation methods for the production of safe crops with lower concentrations of hydrophobic pollutants have not been developed. Herein, we competitively inhibited the binding of MLPs to hydrophobic pollutants, pyrene and dieldrin, in roots by using MLP binding pesticides. By conducting a chemical array screening, we found that MLPs bound compounds with indole- and quinazoline-like structures. Commercially available pesticides amisulbrom and pyrifluquinazon, which possess such structures, successfully inhibited the binding of MLPs to pyrene and dieldrin in vitro. When zucchini plants were cultivated in the contaminated soil with 1.25 mmol/kg pyrene and 12.5 μmol/kg dieldrin, the concentration of pyrene and dieldrin in xylem sap was significantly decreased by 30% and 15%, respectively. Our results demonstrate that the pesticides binding to MLPs competitively inhibited the binding of MLPs to pyrene and dieldrin in roots, resulting in the reduction of overall contamination. This study proposes a novel approach to cultivate safer crops and advances the utilization of unknown functions of pesticides.

The Nicotiana tabacum L. major latex protein-like protein 423 (NtMLP423) positively regulates drought tolerance by ABA-dependent pathway

BACKGROUND

Drought stress is an environmental factor that limits plant growth and reproduction. Little research has been conducted to investigate the MLP gene in tobacco. Here, NtMLP423 was isolated and identified, and its role in drought stress was studied.

RESULTS

Overexpression of NtMLP423 improved tolerance to drought stress in tobacco, as determined by physiological analyses of water loss efficiency, reactive oxygen species levels, malondialdehyde content, and levels of osmotic regulatory substances. Overexpression of NtMLP423 in transgenic plants led to greater sensitivity to abscisic acid (ABA)-mediated seed germination and ABA-induced stomatal closure. NtMLP423 also regulated drought tolerance by increasing the levels of ABA under conditions of drought stress. Our study showed that the transcription level of ABA synthetic genes also increased. Overexpression of NtMLP423 reduced membrane damage and ROS accumulation and increased the expression of stress-related genes under drought stress. We also found that NtWRKY71 regulated the transcription of NtMLP423 to improve drought tolerance.

CONCLUSIONS

Our results indicated that NtMLP423-overexpressing increased drought tolerance in tobacco via the ABA pathway.

PR10/Bet v1-like Proteins as Novel Contributors to Plant Biochemical Diversity

Pathogenesis-related (PR) proteins constitute a broad class of plant proteins with analogues found throughout nature from bacteria to higher eukaryotes. PR proteins were first noted in plants as part of the hypersensitive response, but have since been assigned an array of biological roles. The PR10/Bet v1-like proteins are a subset of PR proteins characterized by an ability to bind a wide range of lipophilic ligands, uniquely positioning them as contributors to specialized biosynthetic pathways. PR10/Bet v1-like proteins participate in the production of plant alkaloids and phenolics including flavonoids, both as general binding proteins and in special cases as catalysts. Owing initially to the perceived allergenic properties of PR10/Bet v1-like proteins, many were studied at the structural level to elucidate the basis for ligand binding. These studies provided a foundation for more recent efforts to understand higher-level structural order and how PR10/Bet v1-like proteins catalyse key reactions in plant pathways. Synthetic biology aimed at reconstituting plant-specialized metabolism in microorganisms uses knowledge of these proteins to fine-tune performance in new systems.

Wheat RING E3 ubiquitin ligase TaDIS1 degrade TaSTP via the 26S proteasome pathway

Drought stress has a great impact on wheat yields. The ubiquitin/26S proteasome system is one of the most important mechanisms employed by plants for responding to stress. E3 ubiquitin ligase is an important part of the ubiquitin/26S proteasome system. In wheat, the mechanism of E3 ubiquitin ligase TaDIS1 has not been investigated in great detail. In this study, TaSTP was identified as an interacting partner using yeast two-hybrid screening. The results obtained from bimolecular fluorescence complementation, pull-down, and co-immunoprecipitation assays also demonstrated that TaDIS1 interacts with TaSTP. In vitro ubiquitination assays showed that TaDIS1 has an E3 ubiquitin ligase activity and the results based on two TaDIS1 mutants suggested that the RING domain is essential for its E3 ubiquitin ligase activity. In addition, we used MG132 to show that TaSTP can be degraded by TaDIS1 via the 26S proteasome pathway. The transcript levels of TaSTP showed that it can also respond to different abiotic stresses, such as drought, salt, and abscisic acid treatment. RING E3 ubiquitin ligase TaDIS1 may through the posttranslational regulation of TaSTP to play an important role in drought tolerance.

Molecular approach to a patient's tailored diagnosis of the oral allergy syndrome

Oral allergy syndrome (OAS) is one of the most common IgE-mediated allergic reactions. It is characterized by a number of symptoms induced by the exposure of the oral and pharyngeal mucosa to allergenic proteins belonging to class 1 or to class 2 food allergens. OAS occurring when patients sensitized to pollens are exposed to some fresh plant foods has been called pollen food allergy syndrome (PFAS). In the wake of PFAS, several different associations of allergenic sources have been progressively proposed and called syndromes. Molecular allergology has shown that these associations are based on IgE co-recognition taking place between homologous allergens present in different allergenic sources. In addition, the molecular approach reveals that some allergens involved in OAS are also responsible for systemic reactions, as in the case of some food Bet v 1-related proteins, lipid transfer proteins and gibberellin regulated proteins. Therefore, in the presence of a convincing history of OAS, it becomes crucial to perform a patient's tailored molecule-based diagnosis in order to identify the individual IgE sensitization profile. This information allows the prediction of possible cross-reactions with homologous molecules contained in other sources. In addition, it allows the assessment of the risk of developing more severe symptoms on the basis of the features of the allergenic proteins to which the patient is sensitized. In this context, we aimed to provide an overview of the features of relevant plant allergenic molecules and their involvement in the clinical onset of OAS. The value of a personalized molecule-based approach to OAS diagnosis is also analyzed and discussed.

A Comprehensive Review on Kiwifruit Allergy: Pathogenesis, Diagnosis, Management, and Potential Modification of Allergens Through Processing

Kiwifruit is rich in bioactive components including dietary fibers, carbohydrates, natural sugars, vitamins, minerals, omega-3 fatty acids, and antioxidants. These components are beneficial to boost the human immune system and prevent cancer and heart diseases. However, kiwifruit is emerging as one of the most common elicitors of food allergies worldwide. Kiwifruit allergy results from an abnormal immune response to kiwifruit proteins and occur after consuming this fruit. Symptoms range from the oral allergy syndrome (OAS) to the life-threatening anaphylaxis. Thirteen different allergens have been identified in green kiwifruit and, among these allergens, Act d 1, Act d 2, Act d 8, Act d 11, and Act d 12 are defined as the "major allergens." Act d 1 and Act d 2 are ripening-related allergens and are found in abundance in fully ripe kiwifruit. Structures of several kiwifruit allergens may be altered under high temperatures or strong acidic conditions. This review discusses the pathogenesis, clinical features, and diagnosis of kiwifruit allergy and evaluates food processing methods including thermal, ultrasound, and chemical processing which may be used to reduce the allergenicity of kiwifruit. Management and medical treatments for kiwifruit allergy are also summarized.

Plant-Made Bet v 1 for Molecular Diagnosis

Allergic disease diagnosis is currently experiencing a breakthrough due to the use of allergenic molecules in serum-based assays rather than allergen extracts in skin tests. The former methodology is considered a very innovative technology compared with the latter, since it is characterized by flexibility and adaptability to the patient's clinical history and to microtechnology, allowing multiplex analysis. Molecular-based analysis requires pure allergens to detect IgE sensitization, and a major goal, to maintain the diagnosis cost-effective, is to limit their production costs. In addition, for the production of recombinant eukaryotic proteins similar to natural ones, plant-based protein production is preferred to bacterial-based systems due to its ability to perform most of the post-translational modifications of eukaryotic molecules. In this framework, Plant Molecular Farming (PMF) may be useful, being a production platform able to produce complex recombinant proteins in short time-frames at low cost. As a proof of concept, PMF has been exploited for the production of Bet v 1a, a major allergen associated with birch (Betula verrucosa) pollen allergy. Bet v 1a has been produced using two different transient expression systems in Nicotiana benthamiana plants, purified and used in a new generation multiplex allergy diagnosis system, the patient-Friendly Allergen nano-BEad Array (FABER). Plant-made Bet v 1a is immunoreactive, binding IgE and inhibiting IgE-binding to the Escherichia coli expressed allergen currently available in the FABER test, thus suggesting an overall similar though non-overlapping immune activity compared with the E. coli expressed form.

A robust method for the estimation and visualization of IgE cross-reactivity likelihood between allergens belonging to the same protein family

Among the vast number of identified protein families, allergens emanate from relatively few families which translates to only a small fraction of identified protein families. In allergy diagnostics and immunotherapy, interactions between immunoglobulin E and allergens are crucial because the formation of an allergen-antibody complex is necessary for triggering an allergic reaction. In allergic diseases, there is a phenomenon known as cross-reactivity. Cross-reactivity describes a situation where an individual has produced antibodies against a particular allergenic protein, but said antibodies fail to discriminate between the original sensitizer and other similar proteins that usually belong to the same family. To expound the concept of cross-reactivity, this study examines ten protein families that include allergens selected specifically for the analysis of cross-reactivity. The selected allergen families had at least 13 representative proteins, overall folds that differ significantly between families, and include relevant allergens with various potencies. The selected allergens were analyzed using information on sequence similarities and identities between members of the families as well as reports on clinically relevant cross-reactivities. Based on our analysis, we propose to introduce a new A-RISC index (Allergens’–Relative Identity, Similarity and Cross-reactivity) which describes homology between two allergens belonging to the same protein family and is used to predict the likelihood of cross-reactivity between them. Information on sequence similarities and identities, as well as on the values of the proposed A-RISC index is used to introduce four categories describing a risk of a cross-reactive reaction, namely: high, medium-high, medium-low and low. The proposed approach can facilitate analysis in component-resolved allergy diagnostics, generation of avoidance guidelines for allergic individuals, and help with the design of immunotherapy.

Integrated Phloem Sap mRNA and Protein Expression Analysis Reveals Phytoplasma-infection Responses in Mulberry

To gain insight into the response of mulberry to phytoplasma-infection, the expression profiles of mRNAs and proteins in mulberry phloem sap were examined. A total of 955 unigenes and 136 proteins were found to be differentially expressed between the healthy and infected phloem sap. These differentially expressed mRNAs and proteins are involved in signaling, hormone metabolism, stress responses, etc. Interestingly, we found that both the mRNA and protein levels of the major latex protein-like 329 (MuMLPL329) gene were increased in the infected phloem saps. Expression of the MuMLPL329 gene was induced by pathogen inoculation and was responsive to jasmonic acid. Ectopic expression of MuMLPL329 in Arabidopsis enhances transgenic plant resistance to Botrytis cinerea, Pseudomonas syringae pv tomato DC3000 (Pst. DC3000) and phytoplasma. Further analysis revealed that MuMLPL329 can enhance the expression of some defense genes and might be involved in altering flavonoid content resulting in increased resistance of plants to pathogen infection. Finally, the roles of the differentially expressed mRNAs and proteins and the potential molecular mechanisms of their changes were discussed. It was likely that the phytoplasma-responsive mRNAs and proteins in the phloem saps were involved in multiple pathways of mulberry responses to phytoplasma-infection, and their changes may be partially responsible for some symptoms in the phytoplasma infected plants.

Current (Food) Allergenic Risk Assessment: Is It Fit for Novel Foods? Status Quo and Identification of Gaps

Food allergies are recognized as a global health concern. In order to protect allergic consumers from severe symptoms, allergenic risk assessment for well-known foods and foods containing genetically modified ingredients is installed. However, population is steadily growing and there is a rising need to provide adequate protein-based foods, including novel sources, not yet used for human consumption. In this context safety issues such as a potential increased allergenic risk need to be assessed before marketing novel food sources. Therefore, the established allergenic risk assessment for genetically modified organisms needs to be re-evaluated for its applicability for risk assessment of novel food proteins. Two different scenarios of allergic sensitization have to be assessed. The first scenario is the presence of already known allergenic structures in novel foods. For this, a comparative assessment can be performed and the range of cross-reactivity can be explored, while in the second scenario allergic reactions are observed toward so far novel allergenic structures and no reference material is available. This review summarizes the current analytical methods for allergenic risk assessment, highlighting the strengths and limitations of each method and discussing the gaps in this assessment that need to be addressed in the near future.

Diagnosing allergic sensitizations in the third millennium: why clinicians should know allergen molecule structures

Diagnostic tests to detect allergic sensitization were introduced at the end of the nineteenth century but only in the late 1990s did the advent of molecular allergology revolutionize the approach to the allergic patient. Personalized Medicine, a medical procedure that separates patients into different groups with different medical decisions, practices and interventions has sanctioned this change. In fact, in the last few years molecular allergology and the observation that not every patient has the same allergic profile, even when allergic to the same allergenic source, has originated the concept "one size does not fit all". This new approach requires the identification of still unknown allergens, but also the more detailed investigation of those already known. In depth studies of the structure-function relationships in allergenic molecules can reveal the structural determinants involved in the IgE-binding. Then, the knowledge of the epitope profile of each allergen and of the environmental/experimental conditions affecting the exposure of IgE-binding epitopes can provide important contributions to the understanding of cross-reaction processes and to the improvement of diagnosis, immunotherapy and the overall patient treatment. The evolution of diagnostic systems cannot ignore these new needs in this field.

Recombinant Allergens in Structural Biology, Diagnosis, and Immunotherapy

The years 1988-1995 witnessed the beginning of allergen cloning and the generation of recombinant allergens, which opened up new avenues for the diagnosis and research of human allergic diseases. Most crystal and solution structures of allergens have been obtained using recombinant allergens. Structural information on allergens allows insights into their evolutionary biology, illustrates clinically observed cross-reactivities, and makes the design of hypoallergenic derivatives for allergy vaccines possible. Recombinant allergens are widely used in molecule-based allergy diagnosis such as protein microarrays or suspension arrays. Recombinant technologies have been used to produce well-characterized, noncontaminated vaccine components with known biological activities including a variety of allergen derivatives with reduced IgE reactivity. Such recombinant hypoallergens as well as wild-type recombinant allergens have been used successfully in several immunotherapy trials for more than a decade to treat birch and grass pollen allergy. As a more recent application, the development of antibody repertoires directed against conformational epitopes during immunotherapy has been monitored by recombinant allergen chimeras. Although much progress has been made, the number and quality of recombinant allergens will undoubtedly increase and keep improving our knowledge in basic scientific investigations, diagnosis, and therapy of human allergic diseases.

Proteomic comparison of Chelidonium majus L. latex in different phases of plant development

Chelidonium majus L. (Papaveraceae) latex is used in traditinonal folk medicine to treat papillae, warts, condylomas, which are visible effects of human papilloma virus (HPV) infections. The aim of this work was to provide new insights into the biology and medicinal use of C. majus milky sap in the flowering and fruit ripening period of the plant by comparing the protein content between samples collected on respective developmental stages using LC-MS-based label-free proteome approach. For quantification, the multiplexed LC-MS data were processed using comparative chemometric approach. Progenesis LC-MS results showed that in green fruit phase (stage IV), comparing to flowering phase (stage III) of plant development, a range of proteins with higher abundance were identified as stress- and defense-related. On the other hand at stage III very intense protein synthesis, processes of transcription, protein folding and active transport of molecules (ABC transporters) are well represented. 2-DE protein maps showed an abundant set of spots with similar MWs (about 30-35 kDa) and pIs (ca. 5.5-6.5), which were identified as major latex proteins (MLPs). Therefore we suggest that biological activity of C. majus latex could be related to its protein content, which shifts during plant development from intense biosynthetic processes (biosynthesis and transport of small molecules, like alkaloids) to plant defense mechanisms against pathogens. Further studies will help to elucidate if these defense-related and pathogenesis-related proteins, like MLP, together with small-molecule compounds, could inhibit viral infection, what could be a step to fully understand the medicinal activity of C. majus latex.

Influence of Geographical Location of Orchards on Green Kiwifruit Bioactive Components

Italy is one of the world's major kiwifruit producers and exporters with orchards located in different areas from the north to the south of the peninsula. This study sought to investigate for the first time the possible influence of the geographical location of kiwifruit orchards on some fruit components, selected because of their involvement in beneficial or negative effects on human health. The fruits harvested in 16 Italian areas were analyzed, and the results obtained show that the observed variations of the relative amounts of total proteins, kiwellin, the major allergen actinidin, ascorbate, polyphenols, and superoxide dismutase (SOD)-like activity seem not to be related to the geographical location of the orchards. In contrast, the high concentration of the nutraceutical peptide kissper seems to have some relationship with the cultivation area. In fact, its amount is much higher in the fruits from the Lazio region, thus providing added value to these kiwifruits.

Structure, stability, and IgE binding of the peach allergen Peamaclein (Pru p 7)

Knowledge of the structural properties of allergenic proteins is a necessary prerequisite to better understand the molecular bases of their action, and also to design targeted structural/functional modifications. Peamaclein is a recently identified 7 kDa peach allergen that has been associated with severe allergic reactions in sensitive subjects. This protein represents the first component of a new allergen family, which has no 3D structure available yet. Here, we report the first experimental data on the 3D-structure of Peamaclein. Almost 75% of the backbone resonances, including two helical stretches in the N-terminal region, and four out of six cysteine pairs have been assigned by 2D-NMR using a natural protein sample. Simulated gastrointestinal digestion experiments have highlighted that Peamaclein is even more resistant to digestion than the peach major allergen Pru p 3. Only the heat-denatured protein becomes sensitive to intestinal proteases. Similar to Pru p 3, Peamaclein keeps its native 3D-structure up to 90°C, but it becomes unfolded at temperatures of 100-120°C. Heat denaturation affects the immunological properties of both peach allergens, which lose at least partially their IgE-binding epitopes. In conclusion, the data collected in this study provide a first set of information on the molecular properties of Peamaclein. Future studies could lead to the possible use of the denatured form of this protein as a vaccine, and of the inclusion of cooked peach in the diet of subjects allergic to Peamaclein.

Structure of ginseng major latex-like protein 151 and its proposed lysophosphatidic acid-binding mechanism

Lysophosphatidic acid (LPA) is a phospholipid growth factor with myriad effects on biological systems. LPA is usually present bound to animal plasma proteins such as albumin or gelsolin. When LPA complexes with plasma proteins, it binds to its cognate receptors with higher affinity than when it is free. Recently, gintonin from ginseng was found to bind to LPA and to activate mammalian LPA receptors. Gintonin contains two components: ginseng major latex-like protein 151 (GLP) and ginseng ribonuclease-like storage protein. Here, the crystal structure of GLP is reported, which belongs to the plant Bet v 1 superfamily, and a model is proposed for how GLP binds LPA. Amino-acid residues of GLP recognizing LPA were identified using site-directed mutagenesis and isothermal titration calorimetry. The resulting GLP mutants were used to study the activation of LPA receptor-dependent signalling pathways. In contrast to wild-type GLP, the H147A mutant did not bind LPA, elicit intracellular Ca2+transients in neuronal cells or activate Ca2+-dependent Cl−channels inXenopusoocytes. Based on these results, a mechanism by which GLP recognizes LPA and its requirement to activate G protein-coupled LPA receptors to elicit diverse biological responses were proposed.

Cotton major latex protein 28 functions as a positive regulator of the ethylene responsive factor 6 in defense against Verticillium dahliae

In this study, we identified a defense-related major latex protein (MLP) from upland cotton (designated GhMLP28) and investigated its functional mechanism. GhMLP28 transcripts were ubiquitously present in cotton plants, with higher accumulation in the root. Expression of the GhMLP28 gene was induced by Verticillium dahliae inoculation and was responsive to defense signaling molecules, including ethylene, jasmonic acid, and salicylic acid. Knockdown of GhMLP28 expression by virus-induced gene silencing resulted in increased susceptibility of cotton plants to V. dahliae infection, while ectopic overexpression of GhMLP28 in tobacco improved the disease tolerance of the transgenic plants. Further analysis revealed that GhMLP28 interacted with cotton ethylene response factor 6 (GhERF6) and facilitated the binding of GhERF6 to GCC-box element. Transient expression assay demonstrated that GhMLP28 enhanced the transcription factor activity of GhERF6, which led to the augmented expression of some GCC-box genes. GhMLP28 proteins were located in both the nucleus and cytoplasm and their nuclear distribution was dependent on the presence of GhERF6. Collectively, these results demonstrate that GhMLP28 acts as a positive regulator of GhERF6, and synergetic actions of the two proteins may contribute substantially to protection against V. dahliae infection in cotton plants.

Structure and function of the peanut panallergen Ara h 8

The incidence of peanut allergy continues to rise in the United States and Europe. Whereas exposure to the major allergens Ara h 1, 2, 3, and 6 can cause fatal anaphylaxis, exposure to the minor allergens usually does not. Ara h 8 is a minor allergen. Importantly, it is the minor food allergens that are thought to be responsible for oral allergy syndrome (OAS), in which sensitization to airborne allergens causes a Type 2 allergic reaction to ingested foods. Furthermore, it is believed that similar protein structure rather than a similar linear sequence is the cause of OAS. Bet v 1 from birch pollen is a common sensitizing agent, and OAS results when patients consume certain fruits, vegetables, tree nuts, and peanuts. Here, we report the three-dimensional structure of Ara h 8, a Bet v 1 homolog. The overall fold is very similar to that of Bet v 1, Api g 1 (celery), Gly m 4 (soy), and Pru av 1 (cherry). Ara h 8 binds the isoflavones quercetin and apigenin as well as resveratrol avidly.