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Title: Expression, purification and crystallization of pecan (Carya illinoinensis) vicilin

item LEE, BORAM - Korean Advanced Institute Of Science And Technology (KAIST)
item Zhang, Renhao
item Du, Wen-Xian
item Grauke, Larry
item McHugh, Tara
item Zhang, Yuzhu

Submitted to: Acta Crystallographica Section F: Structural Biology and Crystallization Communications
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/27/2014
Publication Date: 8/21/2014
Citation: Lee, B., Zhang, R., Du, W., Grauke, L.J., McHugh, T.H., Zhang, Y. 2014. Expression, purification and crystallization of pecan (Carya illinoinensis) vicilin. Acta Crystallographica Section F: Structural Biology and Crystallization Communications. F70:1049-1052. DOI: 10.1107/S2053230X14012369.

Interpretive Summary: Pecans (Carya illinoinensis) are a commercially important tree nut. The U.S. alone produced pecans valued at more than U.S. $670 million in 2011. Pecans are nutritious nuts and can be consumed safely by most people. However, pecans can pose serious risks to people who have allergies. Pecans and other tree nuts are recognized to be among the 8 food groups that cause the majority of food allergies and are required to be labeled in the USA by the Food Allergen Labeling and Consumer Protection Act of 2004 when they are used as ingredients in preparing a food product. Failing to inform the consumer of an allergen source on a product label was one of the leading reasons for recent food recalls. Both allergenic patients and the food industry may become victims of foods containing unlabeled allergen sources. A protein called vicilin has been found to be a food allergen in many foods, including peanut, soy bean and a number of tree nuts. Information about pecan allergens is limited and pecan vicilin has not been studied. This study report the cloning, expression, purification and crystallization of the structural core of pecan vicilin and the result and the reagents generated can be used to understand the allergenicity of food allergens.

Technical Abstract: Tree nuts are responsible for many cases of severe food allergies. Vicilin, the 7S seed storage protein, has been identified as a food allergen in many typss of tree nuts. The vicilin protein consists of an N-terminal low-complexity region with antimicrobial activities and a C-terminal domain that forms a trimeric structure that belongs to the cupin superfamily. In this study, vicilin from pecans (Carya illinoinensis) was isolated and it was expressed in bacteria for the first time. The cupin structural core of the protein, residues 369-792, was purified by metal affinity and gel filtration chromatography to high purity. Vicilin crystals were obtained and the best crystal diffracted to 2.65 Å resolution in the space group P212121.