The C-terminal segment of the 1,3-beta-glucanase Ole e 9 from olive (Olea europaea) pollen is an independent domain with allergenic activity: expression in Pichia pastoris and characterization

Safety evaluation of the food enzyme endo-1,3(4)-β-glucanase from the non-genetically modified Talaromyces versatilis strain PF8

The food enzyme endo-1,3(4)-β-glucanase (3-(1-3;1-4)-β-d-glucan 3(4)-glucanohydrolase; EC 3.2.1.6) is produced with the non-genetically modified Talaromyces versatilis strain PF8 by Erbslöh Geisenheim AG. The food enzyme was free from viable cells of the production organism. It is intended to be used in four food manufacturing processes. Dietary exposure to the food enzyme-total organic solids (TOS) was calculated to be up to 0.110 mg TOS/kg body weight (bw) per day in European populations. Genotoxicity tests did not indicate a safety concern. The systemic toxicity was assessed by means of a repeated dose 90-day oral toxicity study in rats. The Panel identified a no observed adverse effect level of 2229 mg TOS/kg bw per day, the highest dose tested, which when compared with the estimated dietary exposure resulted in a margin of exposure of at least 20,264. A search for homology of the amino acid sequence of the food enzyme to known allergens was made and four matches with respiratory or contact allergens were found. The Panel considered that the risk of allergic reactions upon dietary exposure cannot be excluded, but the likelihood is low. Based on the data provided, the Panel concluded that this food enzyme does not give rise to safety concerns, under the intended conditions of use.

Safety evaluation of the food enzyme endo-1,3(4)-β-glucanase from the non-genetically modified Cellulosimicrobium funkei strain AE-TN

The food enzyme endo-1,3(4)-β-glucanase (3-(1-3;1-4)-β-d-glucan 3(4)-glucanohydrolase; EC 3.2.1.6) is produced with the non-genetically modified Cellulosimicrobium funkei strain AE-TN by Amano Enzyme Inc. The food enzyme was shown to contain viable cells of the production strain, which belongs to a species that has been implicated in opportunistic infections in humans. The food enzyme is intended to be used in baking processes and yeast processing. Dietary exposure to the food enzyme total organic solids (TOS) was estimated to be up to 1.75 mg TOS/kg body weight (bw) per day in European populations. Genotoxicity tests did not raise a safety concern. The systemic toxicity was assessed by means of a repeated dose 90-day oral toxicity study in rats. The Panel identified a no observed adverse effect level of 1,788 mg TOS/kg bw per day, the highest dose tested, which, when compared with the estimated dietary exposure, resulted in a margin of exposure of at least 1,022. A search for the similarity of the amino acid sequence of the food enzyme to known allergens was made and no match was found. The Panel considered that, under the intended conditions of use, the risk of allergic reactions by dietary exposure cannot be excluded, but the likelihood for this to occur is low. However, due to the presence of viable cells of the production strain in the food enzyme, the Panel concluded that the food enzyme cannot be considered safe.

Extra Virgin Olive Oil Quality as Affected by Yeast Species Occurring in the Extraction Process

In extra virgin olive oil (EVOO) extraction process, the occurrence of yeasts that could affect the quality of olive oil was demonstrated. Therefore, in this work, at first, the yeasts occurring during different extractive processes carried out in a Tuscany oil mill, at the beginning, in the middle, and the end of the harvesting in the same crop season, were quantified. Then, possible effects on quality of EVOO caused by the predominant yeast species, possessing specific enzymatic activities, were evaluated. Yeast concentrations were higher in extraction processes at the end of the harvesting. Twelve yeast species showing different isolation frequencies during olive oil extractive process and according to the harvesting date were identified by molecular methods. The yeast species dominating olive oil samples from decanter displayed enzymatic activities, potentially affecting EVOO quality according to zymogram analysis. HS-SPME-GC-MS analysis of the volatile compounds in commercial EVOO, inoculated with three yeast species (Nakazawaea molendini-olei, Nakazawaea wickerhamii, Yamadazyma terventina), pointed out significant differences depending on the strain inoculated. In conclusion, during the olive oil extractive processes, some yeast species colonize the extraction plant and may influence the chemical and sensory characteristics of EVOO depending on the cell concentrations and their enzymatic capabilities.

An Enzymatically Active β-1,3-Glucanase from Ash Pollen with Allergenic Properties: A Particular Member in the Oleaceae Family

Endo-β-1,3-glucanases are widespread enzymes with glycosyl hydrolitic activity involved in carbohydrate remodelling during the germination and pollen tube growth. Although members of this protein family with allergenic activity have been reported, their effective contribution to allergy is little known. In this work, we identified Fra e 9 as a novel allergenic β-1,3-glucanase from ash pollen. We produced the catalytic and carbohydrate-binding domains as two independent recombinant proteins and characterized them from structural, biochemical and immunological point of view in comparison to their counterparts from olive pollen. We showed that despite having significant differences in biochemical activity Fra e 9 and Ole e 9 display similar IgE-binding capacity, suggesting that β-1,3-glucanases represent an heterogeneous family that could display intrinsic allergenic capacity. Specific cDNA encoding Fra e 9 was cloned and sequenced. The full-length cDNA encoded a polypeptide chain of 461 amino acids containing a signal peptide of 29 residues, leading to a mature protein of 47760.2 Da and a pI of 8.66. An N-terminal catalytic domain and a C-terminal carbohydrate-binding module are the components of this enzyme. Despite the phylogenetic proximity to the olive pollen β-1,3-glucanase, Ole e 9, there is only a 39% identity between both sequences. The N- and C-terminal domains have been produced as independent recombinant proteins in Escherichia coli and Pichia pastoris, respectively. Although a low or null enzymatic activity has been associated to long β-1,3-glucanases, the recombinant N-terminal domain has 200-fold higher hydrolytic activity on laminarin than reported for Ole e 9. The C-terminal domain of Fra e 9, a cysteine-rich compact structure, is able to bind laminarin. Both molecules retain comparable IgE-binding capacity when assayed with allergic sera. In summary, the structural and functional comparison between these two closely phylogenetic related enzymes provides novel insights into the complexity of β-1,3-glucanases, representing a heterogeneous protein family with intrinsic allergenic capacity.

The C-terminal domains of two homologous Oleaceae β-1,3-glucanases recognise carbohydrates differently: Laminarin binding by NMR

Ole e 9 and Fra e 9 are two allergenic β-1,3-glucanases from olive and ash tree pollens, respectively. Both proteins present a modular structure with a catalytic N-terminal domain and a carbohydrate-binding module (CBM) at the C-terminus. Despite their significant sequence resemblance, they differ in some functional properties, such as their catalytic activity and the carbohydrate-binding ability. Here, we have studied the different capability of the recombinant C-terminal domain of both allergens to bind laminarin by NMR titrations, binding assays and ultracentrifugation. We show that rCtD-Ole e 9 has a higher affinity for laminarin than rCtD-Fra e 9. The complexes have different exchange regimes on the NMR time scale in agreement with the different affinity for laminarin observed in the biochemical experiments. Utilising NMR chemical shift perturbation data, we show that only one side of the protein surface is affected by the interaction and that the binding site is located in the inter-helical region between α1 and α2, which is buttressed by aromatic side chains. The binding surface is larger in rCtD-Ole e 9 which may account for its higher affinity for laminarin relative to rCtD-Fra e 9.

Molecular characterization of recombinant mus a 5 allergen from banana fruit

Allergy to banana fruit appears to have become an important cause of fruit allergy in Europe. Among five allergens that have been found, beta-1,3-glucanase denoted as Mus a 5 was identified as a candidate allergen for the component-resolved allergy diagnosis of banana allergy. Because of the variations in protein levels in banana fruit, in this study Mus a 5 was produced as a fusion protein with glutathione-S-transferase in Escherichia coli. The recombinant Mus a 5 was purified under native conditions by a combination of affinity, ion-exchange, and reversed phase chromatography. N-terminal sequence was confirmed by Edman degradation and 55 % of the primary structure was identified by mass fingerprint, while the secondary structure was assessed by circular dichroism spectroscopy. IgG reactivity of recombinant protein was shown in 2-D immunoblot with anti-Mus a 5 antibodies, while IgG and IgE binding to natural Mus a 5 was inhibited with the recombinant Mus a 5 in immunoblot inhibition test. IgE reactivity of recombinant Mus a 5 was shown in ELISA within a group of ten persons sensitized to banana fruit. Recombinant Mus a 5 is a novel reagent suitable for the component-resolved allergy diagnosis of banana allergy.

The spectrum of olive pollen allergens. From structures to diagnosis and treatment

Olive tree is one of the main allergy sources in Mediterranean countries. The identification of the allergenic repertoire from olive pollen has been essential for the development of rational strategies of standardization, diagnosis, and immunotherapy, all of them focused to increase the life quality of the patients. From its complex allergogram, twelve allergens - Ole e 1 to Ole e 12 - have been identified and characterized to date. Most of them have been cloned and produced as recombinant forms, whose availability have allowed analyzing their three-dimensional structures, mapping their T-cell and B-cell epitopes, and determining the precise allergenic profile of patients for a subsequent patient-tailored immunotherapy. Protein mutant, hypoallergenic derivatives, or recombinant fragments have been also useful experimental tools to analyze the immune recognition of allergens. To test these molecules before using them for clinic purposes, a mouse model of allergic sensitizations has been used. This model has been helpful for assaying different prophylactic approaches based on tolerance induction by intranasal administration of allergens or hypoallergens, used as free or integrated in different delivery systems, and their findings suggest a promising utilization as nasal vaccines. Exosomes - nanovesicles isolated from bronchoalveolar lavage fluid of tolerogenic mice - have shown immunomodulatory properties, being able to protect mice against sensitization to Ole e 1.

Expression and phylogenetic analyses of the Gel/Gas proteins of Tuber melanosporum provide insights into the function and evolution of glucan remodeling enzymes in fungi

The β(1,3)-glucanosyltransferases of the GH72 family are redundant enzymes that are essential for the formation and dynamic remodeling of the fungal wall during different stages of the life cycle. Four putative genes encoding glycosylphosphatidylinositol (GPI)-anchored β(1,3)-glucanosyltransferases, designated TmelGEL1, TmelGEL2, TmelGEL4 and TmelGAS4, have been annotated in the genome of Tuber melanosporum, an ectomycorrhizal fungus that also produces a hypogeous fruiting body (FB) of great commercial value (black truffle). This work focuses on the characterization and expression of this multigene family by taking advantage of a laser microdissection (LMD) technology that has been used to separate two distinct compartments in the FB, the hyphae and the asci containing the ascospores. Of the four genes, TmelGEL1 was the most up-regulated in the FB compared to the free-living mycelium. Inside the FB, the expression of TmelGEL1 was restricted to the hyphal compartment. A phylogenetic analysis of the Gel/Gas protein family of T. melanosporum was also carried out. A total of 237 GH72 proteins from 51 Ascomycotina and 3 Basidiomycota (outgroup) species were analyzed. The resulting tree provides insight into the evolution of the T. melanosporum proteins and identifies new GH72 paralogs/subfamilies. Moreover, it represents a starting point to formulate new hypotheses on the significance of the striking GH72 gene redundancy in fungal biology.

Analysis of olive allergens

Olive pollen is one of the most important causes of seasonal respiratory allergy in Mediterranean countries, where this tree is intensely cultivated. Besides this, some cases of contact dermatitis and food allergy to the olive fruit and olive oil have been also described. Several scientific studies dealing with olive allergens has been reported, being the information available about them constantly increasing. Up to date, twelve allergens have been identified in olive pollen while just one allergen has been identified in olive fruit. This review article describes considerations about allergen extraction and production, also describing the different methodologies employed in the physicochemical and immunological characterization of olive allergens. Finally, a revision of the most relevant studies in the analysis of both olive pollen and olive fruit allergens is carried out.

Molecular and immunological characterization of Mus a 5 allergen from banana fruit

SCOPE

Banana fruit has become an important cause of fruit allergy in the recent years. Among the five registered IUIS allergens, Mus a 1 and Mus a 2 have been characterized in detail. In this study, molecular characterization and evaluation of the allergenic properties of β-1,3-glucanase from banana (Musa acuminata), denoted as Mus a 5, were performed.

METHODS AND RESULTS

The gene of Mus a 5 was cloned and sequenced. The obtained cDNA revealed a novel Mus a 5 isoform with an open reading frame encoding a protein of 340 amino acids comprising a putative signal peptide of 28 amino acid residues. By MALDI-TOF analysis Mus a 5 isolated from banana fruit revealed a molecular mass of 33451±67 Da. Two Mus a 5 isoforms (pI 7.7 and 8.0) were detected by 2D immunoblot with an identical N-terminal sequence. By mass fingerprint, 76 and 83% of the primary structure was confirmed for the two mature Mus a 5 isoforms, respectively. IgE reactivity to Mus a 5 was found in 74% of patients sensitized to banana fruit. Upregulation of basophil activation markers CD63 and CD203c was achieved with Mus a 5 in a concentration-dependent manner.

CONCLUSION

Mus a 5 is a functional allergen and a candidate for the component-resolved allergy diagnosis of banana allergy.

Understanding patient sensitization profiles in complex pollen areas: a molecular epidemiological study

BACKGROUND

Allergy diagnosis in patients exposed to multiple pollen species is complex and misdiagnosis is often a cause for unsuccessful specific immunotherapy.

OBJECTIVE

We studied the sensitization profile of individual allergens (major, minor and pan-allergens) in pollen-sensitized patients in a region with high exposure to olive pollen by investigating the influence of minor allergens on allergic disease and the association between pan- and minor allergen sensitizations.

METHODS

A panel of 13 purified allergens, which included the most relevant allergens in the area, as well as minor olive allergens and pan-allergens, were screened using a high-capacity technology (ADVIA-Centaur) in 891 patients.

RESULTS

Olive allergy as measured by specific IgE to Ole e 1 was the leading pollinosis in the area. The minor olive allergens Ole e 7 and Ole e 9 were markers of more severe allergic illness. Profilin sensitization was associated mainly with grass allergy, the second most prevalent pollinosis. Salsola kali pollen allergy was the third most common cause of pollinosis in the area. The prevalence of sensitization to the peach allergen Pru p 3, a nonspecific lipid-transfer protein, was notable.

CONCLUSION

Epidemiological analysis by component-resolved diagnosis is a new method, which elucidates the interaction between allergen exposure gradient and patient sensitization. High exposure leads to differential sensitization profiles some of which are associated with more severe allergic conditions. Profilin sensitization, related mainly to grass pollinosis, was a marker of more severe grass pollen sensitization.

Solution structure of the C-terminal domain of Ole e 9, a major allergen of olive pollen

Ole e 9 is an olive pollen allergen belonging to group 2 of pathogenesis-related proteins. The protein is composed of two immunological independent domains: an N-terminal domain (NtD) with 1,3-beta-glucanase activity, and a C-terminal domain (CtD) that binds 1,3-beta-glucans. We have determined the three-dimensional structure of CtD-Ole e 9 (101 amino acids), which consists of two parallel alpha-helices forming an angle of approximately 55 degrees , a small antiparallel beta-sheet with two short strands, and a 3-10 helix turn, all connected by long coil segments, resembling a novel type of folding among allergens. Two regions surrounded by aromatic residues (F49, Y60, F96, Y91 and Y31, H68, Y65, F78) have been localized on the protein surface, and a role for sugar binding is suggested. The epitope mapping of CtD-Ole e 9 shows that B-cell epitopes are mainly located on loops, although some of them are contained in secondary structural elements. Interestingly, the IgG and IgE epitopes are contiguous or overlapped, rather than coincident. The three-dimensional structure of CtD-Ole e 9 might help to understand the underlying mechanism of its biochemical function and to determine possible structure-allergenicity relationships.

Emerging pollen allergens

Numerous pollen allergens have been reported over the last few years. Most of them belong to well-known families of proteins but some others constitute the first member of new allergenic families. Some of the factors that can contribute to the detection and identification of new pollen allergens are: a) advances in the technology tools for molecular analysis; and b) the deep knowledge of many allergenic sources. The combination of these factors has provided vast information on the olive pollen allergogram and the identification of minor allergens that become major ones for a significant population. The close taxonomical relationship between olive tree and ash -both Oleaceae- has permitted to identify Fra e 1 (the Ole e 1-like allergen) in ash pollen and to detect the presence of protein homologues of Ole e 3 and Ole e 6. In the other hand, extensive areas of south Europe are suffering an increasing desertification. As a consequence of this, new botanical species are spontaneously growing in these areas or being used in greening ground programs: Chenopodium album and Salsola kali are some examples recently recognized as allergenic woods. The identification of the complete panel of allergens from the hypersensitizing sources might help to develop more accurate diagnosis, and efficient and safer therapy tools for Type-I allergic diseases.

The Gas family of proteins ofSaccharomyces cerevisiae: characterization and evolutionary analysis

The GAS multigene family of Saccharomyces cerevisiae is constituted by five genes (GAS1-GAS5), but GAS1 was the only one to have been characterized to date. Gas1 is a glycosylphosphatidylinositol-anchored protein predominantly localized in the plasma membrane and is also a representative of family GH72 of glycosidase/transglycosidases, a wide group of yeast and fungal enzymes involved in cell wall assembly. Gas1-Gas5 proteins share a common N-terminal domain but exhibit different C-terminal extensions, in which a domain named Cys-Box is located. This domain is similar to the carbohydrate binding module 43 and is present only in Gas1p and Gas2p. Here we report the expression in P. pastoris of soluble forms of Gas proteins. Gas1, 2, 4 and 5 proteins were secreted with a yield of about 30-40 mg/l of medium, whereas the yield for Gas3p was about three times lower. Gas proteins proved to be N-glycosylated. Purified Gas proteins were tested for enzymatic activity. Gas2, Gas4 and Gas5p showed a beta-(1,3)-glucanosyltransferase activity similar to Gas1p. A phylogenetic tree of the N-terminal regions of family GH72 members was constructed. Two subfamilies of N-terminal regions were distinguished: one subfamily, GH72(+), contains proteins that possess a Cys-box in the C-terminal region, whereas family GH72(-) comprises proteins that lack a Cys-box. On the basis of this net distinction, we speculate that the type of C-tail region imposed constraints to the evolution of the N-terminal portion.

Allergenic contribution of the IgE-reactive domains of the 1,3-beta-glucanase Ole e 9: diagnostic value in olive pollen allergy

BACKGROUND

Designing of methods for an accurate diagnosis is a main goal of allergy research. Olive pollen allergy is currently diagnosed using commercially available pollen extracts that do not allow identification of the molecules that elicit the disease.

OBJECTIVE

To analyze the suitability of using the N- and C-terminal domains (NtD and CtD, respectively) of the 1,3-beta-glucanase Ole e 9, a major allergen from olive pollen, for in vitro diagnosis.

METHODS

Serum samples from 55 olive-allergic patients were assayed using enzyme-linked immunosorbent assay to study hypersensitive patients with IgE reactivity to Ole e 9. The specific IgEs to NtD and CtD, obtained by recombinant technology, were determined by means of immunoblotting, enzyme-linked immunosorbent assay, and inhibition assays.

RESULTS

Thirty-one of 33 serum samples from Ole e 9-allergic patients were IgE reactive to recombinant NtD (rNtD) (n = 26 [79%]), recombinant CtD (rCtD) (n = 22 [67%]), or both (n = 17 [52%]). Nine patients (27%) were exclusively reactive to rNtD and 5 (15%) to rCtD. Inhibition assays of IgE binding to Ole e 9 with a mixture of both domains abolished 90% of the binding, whereas 44% and 45% were abolished when rNtD and rCtD were used, respectively.

CONCLUSIONS

Because sensitization to NtD or CtD of Ole e 9 could be correlated to vegetable food-latex-pollen cross-reactivity processes or to the exacerbation and persistence of asthma, respectively, these molecules could be used in vitro as markers of disease to classify patients and to design a patient-tailored immunotherapy approach.

Variability of Ole e 9 allergen in olive pollen extracts: relevance of minor allergens in immunotherapy treatments

BACKGROUND

Clustered severe adverse reactions to immunotherapy with olive pollen extracts have been occasionally reported in areas where olive trees are extensively grown. Allergic patients from these areas, in addition to the major olive pollen allergen Ole e 1, frequently recognize a recently described allergen, Ole e 9.

OBJECTIVE

We aimed to develop an immunoassay to measure Ole e 9 concentration and to study the variability of this allergen in olive pollen extracts.

METHODS

Monoclonal antibodies (mAb) to Ole e 9 were produced from mice immunized with the pure allergen. One of these mAbs was used to develop a sandwich ELISA with an anti-olive pollen extract rabbit serum as the tracer. Olive pollen batches from several suppliers were analyzed using this method. These batches were also analyzed for Ole e 1 content and biological activity.

RESULTS

A 10-fold variation between the extreme values was found for the biological activity of the batches analyzed. Ole e 1 concentration showed a 25-fold variation. Variability of Ole e 9 concentration was extremely high, up to 161 times. The ratio Ole e 1/Ole e 9 varied in a range from 0.6 to 390.4.

CONCLUSION

The availability of a mAb-based ELISA for Ole e 9 made it possible for us to detect an important source of variability in olive pollen batches. This variability may be the cause of outbreaks of adverse reactions in the course of immunotherapy treatments, which have sometimes been observed among olive-allergic patients living in areas with very high levels of airborne olive pollen.

Prophylactic Intranasal Treatment with Fragments of 1,3-β-Glucanase Olive Pollen Allergen Prevents Airway Inflammation in a Murine Model of Type I Allergy

BACKGROUND

Olive pollen is an important cause of allergy in Mediterranean countries. More than 50% of olive-pollen-allergic patients are sensitized against the 1,3-beta-glucanase Ole e 9. To date, prophylactic and therapeutic treatments using purified recombinant allergens have not been studied in animal models of olive pollen allergy.

METHODS

BALB/c mice were immunized against Ole e 9 combining intraperitoneal injections of the allergen in Al(OH)3 with airway allergen challenges. A prophylactic treatment was performed by intranasal administration of a mixture of the recombinant fragments of the allergen prior to Ole e 9 sensitization. Serum levels of specific IgE, IgG1, IgG2a and IgG2b were measured by ELISA, and total IgE levels by sandwich ELISA. Bronchoalveolar lavage and lungs from mice were collected to study airway inflammation by light microscopy.

RESULTS

BALB/c mice immunized against Ole e 9 developed a predominantly Th2-like immune response with allergen-specific immunoglobulin induction and airway inflammation accompanied by the infiltration of eosinophils, lymphocytes, and neutrophils in the lung. Prophylactic treatment by intranasal application of the recombinant fragments of Ole e 9 avoids airway inflammation induced by sensitization with this allergen although the levels of Ole e 9-specific antibodies remain unchanged.

CONCLUSIONS

Prophylactic intranasal treatment with recombinant fragments of Ole e 9 prevents airway inflammation triggered by immunization to this allergen in a murine model of type I allergy.

An olive pollen protein with allergenic activity, Ole e 10, defines a novel family of carbohydrate-binding modules and is potentially implicated in pollen germination

CBMs (carbohydrate-binding modules) are the most common non-catalytic modules associated with enzymes active in plant cell-wall hydrolysis. They have been frequently identified by amino acid sequence alignments, but only a few have been experimentally established to have a carbohydrate-binding activity. A small olive pollen protein, Ole e 10 (10 kDa), has been described as a major inducer of type I allergy in humans. In the present study, the ability of Ole e 10 to bind several polysaccharides has been analysed by affinity gel electrophoresis, which demonstrated that the protein bound 1,3-beta-glucans preferentially. Analytical ultracentrifugation studies confirmed binding to laminarin, at a protein/ligand ratio of 1:1. The interaction of Ole e 10 with laminarin induced a conformational change in the protein, as detected by CD and fluorescence analyses, and an increase of 3.6 degrees C in the thermal denaturation temperature of Ole e 10 in the presence of the glycan. These results, and the absence of alignment of the sequence of Ole e 10 with that of any classified CBM, indicate that this pollen protein defines a novel family of CBMs, which we propose to name CBM43. Immunolocalization of Ole e 10 in mature and germinating pollen by transmission electron microscopy and confocal laser scanning microscopy demonstrated the co-localization of Ole e 10 and callose (1,3-beta-glucan) in the growing pollen tube, suggesting a role for this protein in the metabolism of carbohydrates and in pollen tube wall re-formation during germination.

Three-dimensional structure of the catalytic domain of the yeast β-(1,3)-glucan transferase Gas1: a molecular modeling investigation

The three-dimensional (3D) structure of the catalytic domain of Gas1p, a protein belonging to the only family of beta-(1,3)-glucan transferases so far identified in yeasts and some pathogenic fungi (family GH-72), has been predicted by combining results derived from threading methods, multiple sequence alignments and secondary-structure predictions. The 3D model has allowed the identification of several residues that are predicted to play a crucial role in structural integrity, substrate recognition and catalysis. In particular, the model of the catalytic domain can be useful for designing site-directed mutagenesis experiments and for developing inhibitors of Gas1p enzymatic activity.

Cloning and Expression of the Olea europaea Allergen Ole e 5, the Pollen Cu/Zn Superoxide Dismutase

BACKGROUND

Recombinant DNA technology does provide pure, well-defined and reproducible products to be used for clinical purposes, by cloning and expressing the cDNA of allergens present in a specific extract. Ole e 5 is a pollen allergen of Olea europaea with an IgE-binding frequency of about 35%, which has been identified as a superoxide dismutase (SOD). The aim of this study was to clone the cDNA of Ole e 5, to express Ole e 5 in Escherichia coli and to characterize its immunoreactivity.

METHODS

cDNA of Ole e 5 was amplified by nested 3'-RACE PCR and cloned in pGEX vector 6P expression vector. After sequencing of some clones and homology analysis, the rOle e 5 was produced in an E. coli strain as a fusion protein with GST and purified. Then, the protein immunoreactivity was evaluated by patients' IgE binding (ELISA, ELISA inhibition, and immunoblotting) and by rabbit anti-rOle e 5 binding (immunoblotting and immunoblotting inhibition).

RESULTS

The sequence analysis of Ole e 5 cDNA confirmed that Ole e 5 is a Cu/Zn SOD, with an identity from 90 to 80% with SOD from other species. rOle e 5 was recognized by IgE from 39% of olive pollen-allergic patients tested; moreover, this binding was inhibited by the olive pollen extract. An anti-rOle e 5 antiserum raised in rabbit strongly reacted with a natural component of about 16-kDa molecular weight present in the olive pollen extract; moreover, this binding was inhibited by the recombinant protein.

CONCLUSIONS

Ole e 5 is the first Cu/Zn SOD identified as an allergen in a pollen source. Due to the widespread presence of this enzyme, rOle e 5 allergen, cloned and expressed in a complete form in E. coli, could represent a good tool to investigate the allergen cross-reactivity between O. europaea pollen and other allergenic sources, such as plant foods and other pollens.

1,3-beta-glucanases as candidates in latex-pollen-vegetable food cross-reactivity

BACKGROUND

1,3-beta-glucanases (group 2 of pathogenesis-related proteins) are enzymes widely distributed among higher plants and have been recently proven to be significant allergens.

OBJECTIVE

The aim of this work was to study the potential implication of 1,3-beta-glucanases in cross-reactivities among latex, pollen and vegetable foods.

METHODS

The cDNA encoding the N-terminal domain (NtD) of Ole e 9, a major allergenic 1,3-beta-glucanase from olive pollen, was amplified by polymerase chain reaction and produced as a recombinant protein in Pichia pastoris (recombinant N-terminal domain, rNtD). Circular dichroism, ELISA, immunoblotting and immunoblotting inhibition experiments were carried out. Sera from olive pollen allergic patients and a rNtD-specific polyclonal antiserum were used.

RESULTS

The NtD of Ole e 9 has been produced at high yield in the yeast P. pastoris and possesses 1,3-beta-glucanase activity. The expressed polypeptide conserves IgE and IgG immunodominant epitopes of the whole Ole e 9. A rNtD-specific polyclonal antiserum and sera from olive pollen allergic patients allowed detection of IgG and IgE reactive peptidic epitopes common to 1,3-beta-glucanase Ole e 9 in extracts from ash and birch pollen, tomato, potato, bell-pepper, banana and latex.

CONCLUSION

rNtD and homologous glucanases are new molecules to be used in diagnostic protocols as they could help to identify allergic pollen patients who are at risk for developing allergic symptoms to fruits, vegetables and latex.

Transition from a Botanical to a Molecular Classification in Tree Pollen Allergy: Implications for Diagnosis and Therapy

Tree pollens are among the most important allergen sources. Allergic cross-reactivity to pollens of trees from various plant orders has so far been classified according to botanical relationships. In this context, cross-reactivities to pollens of trees of the Fagales order (birch, alder, hazel, hornbeam, oak, chestnut), fruits and vegetables, between pollens of the Scrophulariales (olive, ash, plantain, privet, lilac) and pollens of the Coniferales (cedar, cypress, pine) are well established. The application of molecular biology methods for allergen characterization has revealed the molecular nature of many important tree pollen allergens. We review the spectrum of tree pollen allergens and propose a classification of tree pollen and related allergies based on major allergen molecules instead of botanical relationships among the allergenic sources. This molecular classification suggests the major birch pollen allergen, Bet v 1 as a marker for Fagales pollen and related plant food allergies, the major olive pollen allergen, Ole e 1, as a possible marker for Scrophulariales pollen allergy and the cedar allergens, Cry j 1 and Cry j 2, as potential markers for allergy to Coniferales pollens. We exemplify for Fagales pollen allergy and Bet v 1 that major marker allergens are diagnostic tools to determine the disease-eliciting allergen source. Information obtained by diagnostic testing with marker allergens will be important for the appropriate selection of patients for allergen-specific forms of therapy.

A Major Allergen from Pollen Defines a Novel Family of Plant Proteins and Shows Intra- and Interspecie Cross-Reactivity

Olive tree (Olea europaea) pollen is a main cause of allergy associated with extensive areas of Europe and North America. Ole e 10, a small (10.8 kDa) and acidic (pI 5.8) protein, has been identified as a major allergen from the olive pollen, isolated, and characterized. Circular dichroism analysis gave 17% alpha helix, 33% beta sheet, and 21% beta turn for its secondary structure. Based on amino acid sequences of tryptic peptides, the protein was cloned and sequenced. The allergen consists of a single polypeptide chain of 102 aa, with a signal peptide of 21 residues. Ole e 10 showed homology with the C-terminal domain of another olive allergen, Ole e 9 (1,3-beta-glucanase, 53% identity), with deduced sequences from Arabidopsis thaliana genes (42-46% identity) and with polypeptide segments (Cys boxes) of proteins involved in yeast development (Epd1/Gas-1p/Phr2 families; 42-43% similarity). Ole e 10 showed 55% prevalence for olive-allergic patients and exhibited an IgE response dependent on its conformation. Remarkable IgE cross-reactivity was detected with Ole e 9, but no correlation was observed between the individual IgE responses to both allergens. Ole e 10 shares IgE B cell epitopes with proteins from Oleaceae, Gramineae, Betulaceae, Chenopodiaceae, Cupressaceae, Ambrosia, and Parietaria pollens, latex, and vegetable foods, such as tomato, kiwi, potato, and peach. These data indicate that Ole e 10 is a new pan-allergenic plant protein that shows notable intra- and interspecie IgE cross-reactivity and is a powerful candidate to be involved in pollen-latex-fruit syndrome.