A mosquito hemolymph odorant-binding protein family member specifically binds juvenile hormone
A mosquito hemolymph odorant-binding protein family member specifically binds juvenile hormone
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DOI：
10.1074/jbc.m117.802009
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发表时间：
2017-09-15
影响因子：
4.8
通讯作者：
Andersen, John F.
中科院分区：
文献类型：
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作者：
Kim, Il Hwan;Van Pham;Andersen, John F.
保幼激素（JH）是昆虫发育和繁殖的重要调节因子。在成年蚊子中，它是卵巢成熟和正常雄性生殖行为所必需的，但分泌后JH的分布和活性如何调节尚不清楚。在这里，我们报告了一种新的类型的特定JH结合蛋白，命名为蚊幼斑结合蛋白（mJHBP），在蛹和成年埃及伊蚊男性和女性的血淋巴中循环。mJHBP是气味结合蛋白（OBP）家族的成员，并且直系同源物存在于伊蚊、库蚊和按蚊物种的基因组中。使用等温滴定量热法，我们表明，mJHBP特异性结合JH II和JH III，但不花生酸或JH衍生物。mJHBP在JH III存在下结晶，发现具有双OBP结构域结构，使人联想到蚊子的唾液“长”D 7蛋白。我们观察到，一个单一的JH III分子被包含在N-末端结构域结合口袋中，该口袋被C-末端结构域衍生的α-螺旋封闭在明显的构象变化中。配体的电子密度表明JH III的天然10 R对映体的高占有率。值得注意的是，mJHBP在结构上与鳞翅目昆虫的血淋巴JHBP无关。mJHBP在Ae.埃及伊蚊幼虫表明，它主要在成虫阶段活跃，在成虫阶段，它可能影响JH对卵发育、交配行为、进食或其他过程的影响。
Juvenile hormone (JH) is a key regulator of insect development and reproduction. In adult mosquitoes, it is essential for maturation of the ovary and normal male reproductive behavior, but how JH distribution and activity is regulated after secretion is unclear. Here, we report a new type of specific JH-binding protein, given the name mosquito juvenile hormone-binding protein (mJHBP), which circulates in the hemolymph of pupal and adult Aedes aegypti males and females. mJHBP is a member of the odorant-binding protein (OBP) family, and orthologs are present in the genomes of Aedes, Culex, and Anopheles mosquito species. Using isothermal titration calorimetry, we show that mJHBP specifically binds JH II and JH III but not eicosanoids or JH derivatives. mJHBP was crystallized in the presence of JH III and found to have a double OBP domain structure reminiscent of salivary "long" D7 proteins of mosquitoes. We observed that a single JH III molecule is contained in the N-terminal domain binding pocket that is closed in an apparent conformational change by a C-terminal domain-derived alpha-helix. The electron density for the ligand indicated a high occupancy of the natural 10R enantiomer of JH III. Of note, mJHBP is structurally unrelated to hemolymph JHBP from lepidopteran insects. A low level of expression of mJHBP in Ae. aegypti larvae suggests that it is primarily active during the adult stage where it could potentially influence the effects of JH on egg development, mating behavior, feeding, or other processes.