Wang Jing, Yang Litao, Zhao Xiaoxiang, Li Jing, Zhang Dabing
National Center for Molecular Characterization of Genetically Modified Organisms, State Key Laboratory of Hybrid Rice, School of Life Science and Biotechnology, Shanghai Jiao Tong University , 800 Dongchuan Road, Shanghai 200240, People's Republic of China.
J Agric Food Chem. 2014 Jan 8;62(1):270-8. doi: 10.1021/jf402463w. Epub 2013 Dec 20.
Most known allergenic proteins in rice ( Oryza sativa ) seed belong to the Tryp_alpha_amyl family (PF00234), but the sequence characterization and the evolution of the allergenic Tryp_alpha_amyl family members in plants have not been fully investigated. In this study, two specific motifs were found besides the common alpha-amylase inhibitors (AAI) domain from the allergenic Tryp_alpha_amyl family members in rice seeds (trRSAs). To understand the evolution and functional importance of the Tryp_alpha_amy1 family and the specific motifs for the allergenic one, a BLAST search identified 75 homologous proteins of trRSAs (trHAs) from 22 plant species including main crops such as rice, maize ( Zea mays ), wheat ( Triticum aestivum ), and sorghum ( Sorghum bicolor ) from all available sequences in the public databases. Statistical analysis showed that the allergenicity of trHAs is closely associated with these two motifs with high number of cysteine residues (p value = 0.00026), and the trHAs with and without the two motifs were clustered into separate clades, respectively. Furthermore, significant difference was observed on the secondary and tertiary structures of allergenic and nonallergenic trHAs. In addition, expression analysis showed that trHA-encoding genes of purple false brome ( Brachypodium distachyon ), barrel medic ( Medicago truncatula ), rice, and sorghum are dominantly expressed in seeds. This work provides insight into the understanding of the properties of allergens in the Tryp_alpha_amyl family and is helpful for allergy therapy.
水稻（Oryza sativa）种子中大多数已知的致敏蛋白属于胰蛋白酶α-淀粉酶家族（PF00234），但植物中致敏性胰蛋白酶α-淀粉酶家族成员的序列特征和进化尚未得到充分研究。在本研究中，除了水稻种子中致敏性胰蛋白酶α-淀粉酶家族成员（trRSAs）常见的α-淀粉酶抑制剂（AAI）结构域外，还发现了两个特定基序。为了了解胰蛋白酶α-淀粉酶1家族的进化和功能重要性以及致敏性家族的特定基序，通过BLAST搜索从公共数据库中所有可用序列中鉴定出了来自22种植物的75个trRSAs同源蛋白（trHAs），这些植物包括水稻、玉米（Zea mays）、小麦（Triticum aestivum）和高粱（Sorghum bicolor）等主要作物。统计分析表明，trHAs的致敏性与这两个含有大量半胱氨酸残基的基序密切相关（p值 = 0.00026），有和没有这两个基序的trHAs分别聚集成不同的进化枝。此外，在致敏性和非致敏性trHAs的二级和三级结构上观察到了显著差异。另外，表达分析表明，紫羊茅（Brachypodium distachyon）、蒺藜苜蓿（Medicago truncatula）、水稻和高粱中编码trHA的基因在种子中占主导表达。这项工作为理解胰蛋白酶α-淀粉酶家族过敏原的特性提供了见解，并有助于过敏治疗。
