A new pepper allergen Zan b 1.01 of 2S albumins: Identification, cloning, characterization, and cross-reactivity

Authors: LI, HONG - Chinese Academy Of Medical Sciences; ZHU, LIXIA - Hefei University Of Technology; WANG, RUIQI - Chinese Academy Of Medical Sciences; ZHU, LIPING - Chinese Academy Of Medical Sciences; HU, JING - Hefei University Of Technology; CHEN, FENG - Hefei University Of Technology; MA, LI - Morehouse College; TANG, RUI - Chinese Academy Of Medical Sciences; LIU, SIYU - Hefei University Of Technology; NI, KANG - Hefei University Of Technology; YE, XIAODONG - Hefei University Of Technology; Zhang, Yuzhu; SUN, JINLYU - Chinese Academy Of Medical Sciences; JIN, TENGCHUAN - Hefei University Of Technology

Submitted to: Asian Pacific Journal of Allergy and Immunology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/30/2024
Publication Date: 1/6/2024
Citation: Li, H., Zhu, L., Wang, R., Zhu, L., Hu, J., Chen, F., Ma, L., Tang, R., Liu, S., Ni, K., Ye, X., Zhang, Y., Sun, J., Jin, T. 2024. A new pepper allergen Zan b 1.01 of 2S albumins: Identification, cloning, characterization, and cross-reactivity. Journal of Agricultural and Food Chemistry. https://doi.org/10.12932/ap-300423-1595.
DOI: https://doi.org/10.12932/ap-300423-1595

Interpretive Summary: Allergy to sichuan pepper (Zanthoxylum bungeanum Maxim.) was first reported in 2005. However, the main components that cause the allergy were unclear. In this study, we aimed to identify and characterize a novel allergen from sichuan pepper. We isolated a protein around 14 kDa by ionic exchange chromatography and molecular exclusion chromatography. Analytical ultracentrifugation and mass spectrometry showed that it was a 2S albumin similar to an a-AAI domain-containing protein of Citrus sinensis. Circular dichroism spectroscopy showed that its thermal stability is high, possibly due to its disulfide bridges. According to the results of de novo peptide sequencing, the DNA sequence of AAI domain was cloned from the genome of sichuan pepper. Dot blot and ELISA showed that the serum IgE of sichuan pepper allergy patients could recognized the allergen. In addition, cross-reactivities between sichuan pepper and citrus, pistachio, and cashew were studied. This novel 2S albumin allergen from sichuan pepper is now named Zan b 1.

Technical Abstract: Background: Zanthoxylum bungeanum (Sichuan pepper; '' in Chinese) is used as a spice worldwide and is a potentially life-threatening allergenic food source, as first reported by our team in 2005. However, its allergen components are unknown. Objective: We aim to identify and characterize its major allergen and determine its cross-reactivities with citrus seeds, pistachios, and cashew seeds. Methods: Ionic exchange and molecular exclusion chromatography were used to isolate the protein components from Sichuan pepper seed. A protein fraction was characterized by SDS-PAGE, analytical ultracentrifugation, mass spectrometry, and circular dichroism spectroscopy. The coding region of it was amplified from the genome. ELISA and competitive ELISA assays were used to investigate the allergenicity and cross-reactivity of allergens. Results: This protein allergen was around 14 kDa. It was a 2S albumin similar to an a-Amylase inhibitor (AAI) domain-containing protein of Citrus sinensis. Circular dichroism spectroscopy showed its thermal stability was high. A 303 bps DNA sequence of the AAI domain was cloned from the genome of the Sichuan pepper. Competitive ELISA assays showed positive cross-reactivities between this allergen and citrus seeds, pistachios, and cashew seeds. Conclusions: A major allergen of around 14 kDa from Sichuan pepper seed was confirmed, which belongs to the 2S albumin of plant seed storage proteins. Based on the nomenclature of the IUIS Subcommittee for Allergen Nomenclature, this allergen is designated as Zan b 1.01. The cross-reactivities were demonstrated between Zan b 1.01 and citrus seeds, pistachios, and cashew seeds.