Bla g 6:: A troponin C allergen from Blattella germanica with IgE binding calcium dependence
Bla g 6:: A troponin C allergen from Blattella germanica with IgE binding calcium dependence
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DOI：
10.1016/j.jaci.2006.02.017
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发表时间：
2006-06-01
影响因子：
14.2
通讯作者：
Pomes, Anna
中科院分区：
文献类型：
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作者：
Hindley, James;Wunschmann, Sabina;Pomes, Anna
背景：已知的蟑螂变应原似乎不能解释全部的IgE反应。目的：鉴定和研究其他与蟑螂过敏有关的德国小蠊变应原的重要性。克隆并在巴斯德毕赤酵母中表达了3种肌钙蛋白C等变应原(BlAg6)。用Swiss-Model进行同源建模。用荧光多路阵列系统同时检测了104份血清对纯化变应原的免疫球蛋白E反应。结果：鉴定出3个与昆虫肌钙蛋白Cs和脊椎动物钙调蛋白同源(氨基酸同源性分别为61%~78%和42%~44%)的变应原Bla g 6.0101、Bla g 6.0201和Bla g 6.0301，并具有2个EF手性钙结合区。Bla g 6的分子模型显示，两个结构上同源的小叶由一个连接子连接，该连接子赋予过敏原灵活性。重组Bla-g-6与IgE结合率为14%。10 mmoL/L乙二醇双-(β-氨基乙醚)-N，N，N‘，N’-四乙酸钙耗竭对大多数情况下的IgE结合无明显影响。有趣的是，在钙缺乏后添加10 mmoL/L CaCl2使IgE结合量增加约2倍，这是以前没有关于钙结合性过敏原的发现。结论：Bla g 6是一种肌钙蛋白变应原，具有钙依赖的IgE反应性，可能参与肌肉收缩。临床意义：BLA g 6同源过敏原可能发生在其他昆虫中，并引起共敏感或过敏性交叉反应。
Background: The known cockroach allergens do not appear to account for the full repertoire of IgE responses.Objective: To identify and investigate the importance of other Blattella germanica allergens contributing to cockroach allergy.Methods: A B germanica cDNA library was screened with pooled sera from patients with cockroach allergy. Three isoallergens of troponin C (Bla g 6) were cloned and expressed in Pichia pastoris. Homology modeling was performed by using Swiss-Model. IgE responses to purified allergens were simultaneously measured in 104 sera by using a fluorescent multiplex array system. The effect of calcium on IgE binding was investigated by ELISA.Results: Three isoallergens, Bla g 6.0101, Bla g 6.0201, and Bla g 6.0301, were identified which share homology with insect troponin Cs and vertebrate calmodulins (61% to 78% and 42% to 44% amino acid identity, respectively) and have 2 EF-hand calcium binding domains. Molecular models of Bla g 6 showed 2 structurally homologous lobes connected by a linker that confers flexibility to the allergen. The prevalence of IgE binding to recombinant Bla g 6 was 14%. Calcium depletion by 10 mmol/L ethyleneglycol-bis-(beta-aminoethylether)-N,N,N',N'-tetraacetic acid did not significantly affect IgE binding in most cases. Interestingly, addition of 10 mmol/L CaCl2 after calcium depletion increased IgE binding by approximately 2-fold, a finding not previously reported for calcium binding allergens.Conclusion: Bla g 6 is a troponin allergen with a calcium dependent IgE reactivity that may be involved in muscle contraction. Clinical implications: Bla g 6 homologous allergens may occur among other insects and cause cosensitization or allergenic cross-reactivity.