Crystal Structure of Sol i 2: A Major Allergen from Fire Ant Venom
Crystal Structure of Sol i 2: A Major Allergen from Fire Ant Venom
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DOI：
10.1016/j.jmb.2011.10.009
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发表时间：
2012-01-27
影响因子：
5.6
通讯作者：
Markovic-Housley, Zora
中科院分区：
文献类型：
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作者：
Borer, Aline S.;Wassmann, Paul;Markovic-Housley, Zora
Sol i 2是一种来自红火蚁毒液的强效过敏原，其中含有已知是过敏反应的强力触发剂的过敏原Sol i 1、Sol i 2、Sol i 3和Sol i 4。Sol i 2导致约三分之一被火蚁蜇伤的个体产生IgE抗体。杆状病毒重组二聚体Sol i 2结晶为天然和硒代甲硫酰衍生的蛋白质，其结构已确定在2.6埃分辨率的单波长反常色散。每个亚基的整体折叠由包围中央疏水腔的五个螺旋组成。结构由三个分子内二硫键和一个分子间二硫键稳定。最接近的结构同源物是果蝇的序列无关的气味结合蛋白和信息素结合蛋白LUSH，这可能表明类似的生物学功能。为了验证这一假设，我们测量了各种信息素，植物气味剂，和其他配体的可逆结合溶胶i 2的N-苯基-1-萘胺荧光发射的变化后，与N-苯基-1-萘胺竞争的配体的结合。最高的结合亲和力被观察到的疏水配体，如蚜虫报警信息素（E）-β-法呢烯，类似物的蚂蚁报警信息素，和植物挥发物癸烷，十一烷，β-carbellene。可以想象，Sol i 2可以在捕获和/或运输小的疏水配体如信息素、气味、脂肪酸或短寿命疏水引物中起作用。分子表面分析，结合序列比对，可以解释一些蚂蚁物种之间观察到的血清学交叉反应。(C)2011爱思唯尔有限公司版权所有。
Sol i 2 is a potent allergen from the venom of red imported fire ant, which contains allergens Sol i 1, Sol i 2, Sol i 3, and Sol i 4 that are known to be powerful triggers of anaphylaxis. Sol i 2 causes IgE antibody production in about one-third of individuals stung by fire ants. Baculovirus recombinant dimeric Sol i 2 was crystallized as a native and selenomethionyl-derivatized protein, and its structure has been determined by single-wavelength anomalous dispersion at 2.6 angstrom resolution. The overall fold of each subunit consists of five helices that enclose a central hydrophobic cavity. The structure is stabilized by three intramolecular disulfide bridges and one intermolecular disulfide bridge. The nearest structural homologue is the sequence-unrelated odorant binding protein and pheromone binding protein LUSH of the fruit fly Drosophila, which may suggest a similar biological function. To test this hypothesis, we measured the reversible binding of various pheromones, plant odorants, and other ligands to Sol i 2 by the changes in N-phenyl-1-naphthylamine fluorescence emission upon binding of ligands that compete with N-phenyl-1-naphthylamine. The highest binding affinity was observed for hydrophobic ligands such as aphid alarm pheromone (E)-beta-farnesene, analogs of ant alarm pheromones, and plant volatiles decane, undecane, and beta-caryophyllene. Conceivably, Sol i 2 may play a role in capturing and/or transporting small hydrophobic ligands such as pheromones, odors, fatty acids, or short-living hydrophobic primers. Molecular surface analysis, in combination with sequence alignment, can explain the serological cross-reactivity observed between some ant species. (C) 2011 Elsevier Ltd. All rights reserved.