ABSTRACT
The effects of desiccation on the early development stages of Mazzaella laminarioides, Scytosiphon lomentaria and Lessonia nigrescens, algal species with different patterns of distribution across the intertidal zone, were examined in the laboratory. In addition, the protective effect against desiccation was evaluated using algal extracts, including those from Porphyra columbina, a macroalga tolerant to desiccation that lives in the uppermost part of the intertidal zone. Our results showed that M. laminarioides displayed the highest resistance to daily desiccation, followed by S. lomentaria, whereas L. nigrescens was the most susceptible. Spores from L. nigrescens exposed to desiccation, although being able to germinate, ceased further post-germination development. In addition, our results showed that all species exposed to extracts from desiccated P. columbina successfully completed their development and strongly suggest the occurrence of compounds with protective properties that help in attenuating the stress caused by desiccation. Finally, our results indicate that the magnitude of the effects generated by desiccation on the early algal development is related to the position of the species in the intertidal zone, and that the protective effects of P. columbina extracts reveal an exceptional metabolism of this species under desiccation stress.
Subject(s)
Desiccation , Plant Extracts/pharmacology , Porphyra/metabolism , Seaweed/growth & development , Cell Survival , Chromatography, Liquid/methods , Metabolome , Plant Extracts/metabolism , Plant Proteins/metabolism , Plant Proteins/pharmacology , Porphyra/physiology , Seaweed/drug effects , Seaweed/physiology , Species Specificity , Spectrometry, Mass, Electrospray Ionization , Spores/growth & development , Spores/physiology , Stress, PhysiologicalABSTRACT
Jug r 1, the 2S albumin allergen from walnut, was isolated from ripe nuts as a native allergen and expressed in Escherichia coli using the Gateway technology as a recombinant allergen. The recombinant Jug r 1 (15 kDa) differs from the native allergen by the absence of cleavage of the polypeptide chain in two covalently associated light (3.5 kDa) and heavy (8 kDa) chains. Recombinant rJug r 1 adopts the canonical alpha-helical fold of plant 2S albumins as checked on CD spectra. Four IgE-binding epitopic stretches were identified along the amino acid sequence of Jug r 1 and localized on the molecular surface of the modeled allergen. Both native and recombinant allergens exhibit similar IgE-binding activity and similarly trigger the degranulation of a FcepsilonRI-expressing rat basophilic leukaemia cell line previously treated by IgE-containing sera. Native Jug r 1 resists to heat denaturation and to the proteolytic attack of trypsin and chymotrypsin but is readily hydrolyzed in the presence of pepsin at acidic pH after 1 h of incubation at 37 degrees C in vitro. Recombinant Jug r 1 could be used for a component-resolved diagnosis of food-allergy.
Subject(s)
2S Albumins, Plant/metabolism , Antigens, Plant/metabolism , Juglans/metabolism , Recombinant Proteins/metabolism , 2S Albumins, Plant/chemistry , 2S Albumins, Plant/genetics , Animals , Antigens, Plant/chemistry , Antigens, Plant/genetics , Binding Sites , Cell Line, Tumor , Epitopes/chemistry , Epitopes/genetics , Escherichia coli/genetics , Escherichia coli/metabolism , Immunoglobulin E/metabolism , Juglans/genetics , Protein Folding , Protein Structure, Secondary , Protein Structure, Tertiary , Rats , Recombinant Proteins/chemistry , Recombinant Proteins/geneticsABSTRACT
The three-dimensional model built for the 13S globulin allergen of buckwheat (Fagopyrum esculentum) consists of three protomers exhibiting the cupin motif, arranged in a homotrimer around a three-fold symmetry axis. Using the SPOT technique, 11 continuous IgE-binding epitopic peptides were characterized on the molecular surface of the 13S globulin allergen of buckwheat. Except for one of them, they all correspond to well exposed regions containing electropositiveley and/or electronegatively charged residues, which cover up to 40% of the molecular surface of the allergen. Some of these epitopes come in close contact to probably create more extended discontinuous epitopes, especially those located on the edge of the 13S globulin homotrimer. Half of the identified epitope peptides remain unaltered in a core structure protected against hydrolysis by digestive proteases and are thus assumed to promote the allergenicity of the 13S globulin. In addition, a few of these epitopes coincide with sequential IgE-binding epitopes previously characterized in soybean 11S globulins, that could account for the IgE-binding cross-reactions observed between soybean and buckwheat in Western blot experiments.
Subject(s)
Allergens/chemistry , Epitope Mapping , Epitopes/chemistry , Epitopes/immunology , Fagopyrum/chemistry , Globulins/chemistry , Immunoglobulin E/immunology , Allergens/immunology , Amino Acid Sequence , Binding Sites , Blotting, Western , Fagopyrum/immunology , Globulins/immunology , Humans , Immunoglobulin E/blood , Models, Molecular , Molecular Sequence Data , Peptide Fragments/chemistry , Peptide Fragments/immunology , Seeds/chemistry , Seeds/immunology , Sequence Alignment , Static ElectricityABSTRACT
Surface-exposed IgE-binding epitopes of close overall conformation were characterized on the molecular surface of three-dimensional models built for the vicilin allergens of peanut (Ara h 1), walnut (Jug r 2), hazelnut (Cor a 11) and cashew nut (Ana o 1). They correspond to linear stretches of conserved amino acid sequences mainly located along the C-terminus of the polypeptide chains. A glyco-epitope corresponding to an exposed N-glycosylation site could also interfere with the IgE-binding epitopes. All these epitopic regions should participate in the IgE-binding cross-reactivity commonly reported between tree nuts or between peanut and some tree nuts in sensitized individuals. Owing to this epitopic community which constitutes a risk of cross-sensitization, the avoidance or a restricted consumption of other tree nuts should be recommended to peanut-sensitized individuals.
Subject(s)
Magnoliopsida/immunology , Nuts/immunology , Plant Proteins/immunology , Anacardium/immunology , Arachis , Binding Sites , Conserved Sequence , Corylus/immunology , Cross Reactions/immunology , Epitopes/metabolism , Hypersensitivity , Immunoglobulin E/metabolism , Juglans/immunology , Seed Storage ProteinsABSTRACT
Linear IgE-binding epitopes identified in legumin allergens of peanut (Ara h 3) and other allergenic tree nuts (Jug r 4 of walnut, Cor a 9 of hazelnut, Ana o 2 cashew nut) were mapped on three-dimensional models of the proteins built up by homology modelling. A conformational analysis revealed that consensual surface-exposed IgE-binding epitopes exhibited some structural homology susceptible to account for the IgE-binding cross-reactivity observed among peanut and tree nut allergens. This structurally related cross-reactivity seems irrespective of the botanical origin of the allergens and thus demands that persons allergic to peanut avoid other three nuts to prevent possible allergic reactions. IgE-binding epitopes similar to those found in 11S globulin allergens do not apparently occur in other vicilin allergens with the cupin fold from peanut (Ara h 1) or tree nuts (Jug r 2 of walnut, Cor a 1 of hazel nut, Ana o 3 of cashew nut).
