Ligand-binding properties of a juvenile hormone receptor, Methoprene-tolerant
Ligand-binding properties of a juvenile hormone receptor, Methoprene-tolerant
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DOI：
10.1073/pnas.1116123109
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发表时间：
2011-12-27
影响因子：
11.1
通讯作者：
Jindra, Marek
中科院分区：
文献类型：
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作者：
Charles, Jean-Philippe;Iwema, Thomas;Jindra, Marek
保幼激素(JH)是一种对昆虫发育至关重要的倍半萜类化合物，但JH信号转导的分子基础尚不清楚，主要是因为JH受体的真实性尚未确定。越来越多的证据表明，碱性螺旋-环-螺旋(BHLH)/Per-Arnt-Sim(PAS)结构域蛋白耐甲基丁二烯(Met)是最佳的JH受体候选。然而，Met如何传递荷尔蒙信号的细节尚不清楚。在这里，我们证明了Met通过其C端的PAS结构域与JH III及其生物活性模拟物甲基丁二烯和吡丙草醚特异性结合。个别氨基酸的取代，预计会形成一个配体结合口袋，残基具有更大的侧链，减少JH III结合，可能是因为空间位阻。虽然取消JH III结合的突变不影响在没有甲基丁二烯的情况下形成的Met-Met复合体，但它阻止了Met-Met二聚体的配体依赖的解离和Met与其伴侣bHLH-PAS蛋白Taiman的配体依赖的相互作用。这些结果表明，Met可以通过直接、特异的结合来感知JH信号，从而建立一类独特的细胞内激素受体。
Juvenile hormone (JH) is a sesquiterpenoid of vital importance for insect development, yet the molecular basis of JH signaling remains obscure, mainly because a bona fide JH receptor has not been identified. Mounting evidence points to the basic helix-loop-helix (bHLH)/Per-Arnt-Sim (PAS) domain protein Methoprene-tolerant (Met) as the best JH receptor candidate. However, details of how Met transduces the hormonal signal are missing. Here, we demonstrate that Met specifically binds JH III and its biologically active mimics, methoprene and pyriproxyfen, through its C-terminal PAS domain. Substitution of individual amino acids, predicted to form a ligand-binding pocket, with residues possessing bulkier side chains reduces JH III binding likely because of steric hindrance. Although a mutation that abolishes JH III binding does not affect a Met-Met complex that forms in the absence of methoprene, it prevents both the ligand-dependent dissociation of the Met-Met dimer and the ligand-dependent interaction of Met with its partner bHLH-PAS protein Taiman. These results show that Met can sense the JH signal through direct, specific binding, thus establishing a unique class of intracellular hormone receptors.