Impact of lipid binding on the tertiary structure and allergenic potential of Jug r 3, the non-specific lipid transfer protein from walnut.
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ABSTRACT:
SUBMITTER: Dubiela P
PROVIDER: S-EPMC6376136 | biostudies-literature | 2019 Feb
REPOSITORIES: biostudies-literature
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Impact of lipid binding on the tertiary structure and allergenic potential of Jug r 3, the non-specific lipid transfer protein from walnut.
Dubiela Pawel P Del Conte Rebecca R Cantini Francesca F Borowski Tomasz T Aina Roberta R Radauer Christian C Bublin Merima M Hoffmann-Sommergruber Karin K Alessandri Stefano S
Scientific reports 20190214 1
Plant non-specific lipid transfer proteins type 1 (nsLTP1) are small basic proteins with a hydrophobic cavity able to host a number of different ligands: i.e. fatty acids, fatty acyl-CoA, phospholipids, glycolipids, and hydroxylated fatty acids. However, ligand binding specificity differs among nsLTPs. Within this protein family, Jug r 3 from walnut has been identified as a major allergen. So far, data on the structural characterization of Jug r 3 and its lipid binding capacity are lacking. We r ...[more]
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Project description:BackgroundPlant lipid transfer proteins (LTPs) assemble a family of small (7-9 kDa) ubiquitous cationic proteins with an ability to bind and transport lipids as well as participate in various physiological processes including defense against phytopathogens. They also form one of the most clinically relevant classes of plant allergens. Nothing is known to date about correlation between lipid-binding and IgE-binding properties of LTPs. The garden pea Pisum sativum is widely consumed crop and important allergenic specie of the legume family. This work is aimed at isolation of a novel LTP from pea seeds and characterization of its structural, functional, and allergenic properties.ResultsThree novel lipid transfer proteins, designated as Ps-LTP1-3, were found in the garden pea Pisum sativum, their cDNA sequences were determined, and mRNA expression levels of all the three proteins were measured at different pea organs. Ps-LTP1 was isolated for the first time from the pea seeds, and its complete amino acid sequence was determined. The protein exhibits antifungal activity and is a membrane-active compound that causes a leakage from artificial liposomes. The protein binds various lipids including bioactive jasmonic acid. Spatial structure of the recombinant uniformly (13)C,(15)N-labelled Ps-LTP1 was solved by heteronuclear NMR spectroscopy. In solution the unliganded protein represents the mixture of two conformers (relative populations ~ 85:15) which are interconnected by exchange process with characteristic time ~ 100 ms. Hydrophobic residues of major conformer form a relatively large internal tunnel-like lipid-binding cavity (van der Waals volume comes up to ~1000 Å(3)). The minor conformer probably corresponds to the protein with the partially collapsed internal cavity.ConclusionsFor the first time conformational heterogeneity in solution was shown for an unliganded plant lipid transfer protein. Heat denaturation profile and simulated gastrointestinal digestion assay showed that Ps-LTP1 displayed a high thermal and digestive proteolytic resistance proper for food allergens. The reported structural and immunological findings seem to describe Ps-LTP1 as potential cross-reactive allergen in LTP-sensitized patients, mostly Pru p 3(+) ones. Similarly to allergenic LTPs the potential IgE-binding epitope of Ps-LTP1 is located near the proposed entrance into internal cavity and could be involved in lipid-binding.
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Project description:Non-specific lipid transfer proteins (LTPs) are a family of lipid-binding molecules that are widely distributed across flowering plant species, many of which have been identified as allergens. They are highly resistant to simulated gastroduodenal proteolysis, a property that may play a role in determining their allergenicity and it has been suggested that lipid binding may further increase stability to proteolysis. It is demonstrated that LTPs from wheat and peach bind a range of lipids in a variety of conditions, including those found in the gastroduodenal tract. Both LTPs are initially cleaved during gastroduodenal proteolysis at three major sites between residues 39-40, 56-57 and 79-80, with wheat LTP being more resistant to cleavage than its peach ortholog. The susceptibility of wheat LTP to proteolyic cleavage increases significantly upon lipid binding. This enhanced digestibility is likely to be due to the displacement of Tyr79 and surrounding residues from the internal hydrophobic cavity upon ligand binding to the solvent exposed exterior of the LTP, facilitating proteolysis. Such knowledge contributes to our understanding as to how resistance to digestion can be used in allergenicity risk assessment of novel food proteins, including GMOs.
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Project description:Tomato (Solanum lycopersicum) is one of the most extensively consumed vegetables but, unfortunately, it is also able to induce allergic reactions. In the past, it has been shown that the choice of tomato cultivar significantly influenced the allergic reaction of tomato allergic subjects. In this study we investigated the allergenic potential of the cultivated tomato line M82 and of two selected lines carrying small chromosome regions from the wild species Solanum pennellii (i.e. IL7-3 and IL12-4). We evaluated the positive interactions of IgEs of allergic subjects in order to investigate the different allergenic potential of the lines under investigation. We used proteomic analyses in order to identify putative tomato allergens. In addition, bioinformatic and transcriptomic approaches were applied in order to analyse the structure and the expression profiles of the identified allergen-encoding genes. These analyses demonstrated that fruits harvested from the two selected introgression lines harbour a different allergenic potential as those from the cultivated genotype M82. The different allergenicity found within the three lines was mostly due to differences in the IgE recognition of a polygalacturonase enzyme (46 kDa), one of the major tomato allergens, and of a pectin methylesterase (34 kDa); both the proteins were more immunoreactive in IL7-3 compared to IL12-4 and M82. The observed differences in the allergenic potential were mostly due to line-dependent translational control or post-translational modifications of the allergens. We demonstrated, for the first time, that the introgression from a wild species (S. pennellii) in the genomic background of a cultivated tomato line influences the allergenic properties of the fruits. Our findings could support the isolation of favorable wild loci promoting low allergenic potential in tomato.
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Project description:The non-specific lipid transfer proteins (LTPs) constitute a large protein family found in all land plants. They are small proteins characterized by a tunnel-like hydrophobic cavity, which makes them suitable for binding and transporting various lipids. The LTPs are abundantly expressed in most tissues. In general, they are synthesized with an N-terminal signal peptide that localizes the protein to spaces exterior to the plasma membrane. The in vivo functions of LTPs are still disputed, although evidence has accumulated for a role in the synthesis of lipid barrier polymers, such as cuticular waxes, suberin, and sporopollenin. There are also reports suggesting that LTPs are involved in signaling during pathogen attacks. LTPs are considered as key proteins for the plant's survival and colonization of land. In this review, we aim to present an overview of the current status of LTP research and also to discuss potential future applications of these proteins. We update the knowledge on 3D structures and lipid binding and review the most recent data from functional investigations, such as from knockout or overexpressing experiments. We also propose and argument for a novel system for the classification and naming of the LTPs.
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Project description:Non-specific lipid-transfer proteins (nsLTPs) represent a family of ubiquitous plant proteins belonging to the prolamin superfamily. nsLTPs are characterized by a globular ?-helical structure stabilized by four disulfide bonds and a hydrophobic cavity which acts as ligand-binding site for a broad spectrum of lipids and hydrophobic molecules. nsLTPs are involved in membrane biogenesis and in the adaption of plants to abiotic and biotic stress. They display antimicrobial activity by the ability to permeabilize the cell membrane of phytopathogens. Moreover, in the presence of lipids, nsLTPs are suggested to activate the plant immune system by a receptor-dependent mechanism. Additionally, nsLTPs from pollen and plant-derived food, in particular type 1 nsLTPs (9?kDa), are described as potent allergens. Within the nsLTP family Pru p 3 from peach is the clinically most relevant allergen which can cause genuine food allergy and frequently elicits severe clinical reactions. So far, the allergenic properties of nsLTPs are attributed to both their low molecular mass and their high thermal and proteolytic stability which allow them to reach the immune system in a biological intact form. Recently, the interaction of nsLTPs with lipids has been suggested to increase their allergenic properties and to promote the allergic sensitization to these proteins. This review will summarize the current knowledge on diversity of lipid ligands of plant LTPs, and illustrate recent studies performed with allergenic nsLTPs to investigate the effect of lipid binding on the structural modification and IgE-binding properties of proteins, and finally the potential effect on the innate immune responses.
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Project description:Background:Non-specific Lipid Transfer Proteins (nsLTPs) are widely distributed in the plant kingdom and constitute a superfamily of related proteins. Several hundreds of different nsLTP sequences-and counting-have been characterized so far, but their biological functions remain unclear. It has been clear for years that they present a certain interest for agronomic and nutritional issues. Deciphering their functions means collecting and analyzing a variety of data from gene sequence to protein structure, from cellular localization to the physiological role. As a huge and growing number of new protein sequences are available nowadays, extracting meaningful knowledge from sequence-structure-function relationships calls for the development of new tools and approaches. As nsLTPs show high evolutionary divergence, but a conserved common right handed superhelix structural fold, and as they are involved in a large number of key roles in plant development and defense, they are a stimulating case study for validating such an approach. Methods:In this study, we comprehensively investigated 797 nsLTP protein sequences, including a phylogenetic analysis on canonical protein sequences, three-dimensional structure modeling and functional annotation using several well-established bioinformatics programs. Additionally, two integrative methodologies using original tools were developed. The first was a new method for the detection of (i) conserved amino acid residues involved in structure stabilization and (ii) residues potentially involved in ligand interaction. The second was a structure-function classification based on the evolutionary trace display method using a new tree visualization interface. We also present a new tool for visualizing phylogenetic trees. Results:Following this new protocol, an updated classification of the nsLTP superfamily was established and a new functional hypothesis for key residues is suggested. Lastly, this work allows a better representation of the diversity of plant nsLTPs in terms of sequence, structure and function.
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