Purification, identification and preliminary crystallographic studies of an allergenic protein from Solanum melongena

Seed Storage Protein, Functional Diversity and Association with Allergy

Plants are essential for humans as they serve as a source of food, fuel, medicine, oils, and more. The major elements that are utilized for our needs exist in storage organs, such as seeds. These seeds are rich in proteins, show a broad spectrum of physiological roles, and are classified based on their sequence, structure, and conserved motifs. With the improvements to our knowledge of the basic sequence and our structural understanding, we have acquired better insights into seed proteins and their role. However, we still lack a systematic analysis towards understanding the functional diversity associated within each family and their associations with allergy. This review puts together the information about seed proteins, their classification, and diverse functional roles along with their associations with allergy.

Solanum melongena allergy (A comprehensive review)

The Solanaceae family, including, among other, eggplants, represents the sixth most widely cultivated crops around the globe. We review the current data regarding allergies to Solanum melongena (eggplants), generating symptoms that range from gastrointestinal to respiratory allergic reactions. Currently, there are more than 4 mechanisms and molecules presumably involved in triggering allergic reactions to Solanum melongena: The lipid transfer protein (LTP) pathway, the profilin pathway, polyphenol oxidase (PPO) mechanism and other molecules. Allergies may be triggered both by pollen respiratory reactions and fruit intake. There is also an important cross-reactivity mechanism revealed by recent studies. Our literature review revealed many case series studies, some with in-depth molecular analysis of the triggering mechanism. However, wide population studies are still scarce. Current geographical distribution of the crops and population migrations should enhance the awareness of allergy and immunology specialists, ENT specialists, emergency physicians and pediatricians to the need for proper routine laboratory testing for possible Solanum allergy.

Crystal structure of the vicilin from Solanum melongena reveals existence of different anionic ligands in structurally similar pockets

Crystal structure of a vicilin, SM80.1, was determined towards exploring its possible physiological functions. The protein was purified from Solanum melongena by combination of ammonium sulphate fractionation and size exclusion chromatography. Structure was determined ab initio at resolution of 1.5 Å by X-ray crystallography showing the three-dimensional topology of the trimeric protein. Each monomer of SM80.1 consists of two similar domains with hydrophobic binding pocket and each accommodating different ligands, i.e. acetate and pyroglutamate. The relatively high stability of these independent anionic ligands in similar pockets indicated a strict requirement of stabilization by hydrogen bonds with the charged residues, suggesting a degree of plasticity within the binding pocket. Comparison of SM80.1 structure with those of other 7S vicilins indicated conservation of putative binding pocket for anionic ligands. Here we propose the possibility of trapping of these ligands in the protein for their requirement in the metabolic processes.