Institute of Entomology, Biology Center, Czech Academy of Sciences, Ceske Budejovice 37005, Czech Republic.
Faculty of Science, University of South Bohemia, Ceske Budejovice 37005, Czech Republic.
Proc Natl Acad Sci U S A. 2022 Nov 29;119(48):e2215541119. doi: 10.1073/pnas.2215541119. Epub 2022 Nov 21.
Juvenile hormones (JHs) control insect metamorphosis and reproduction. JHs act through a receptor complex consisting of methoprene-tolerant (Met) and taiman (Tai) proteins to induce transcription of specific genes. Among chemically diverse synthetic JH mimics (juvenoids), some of which serve as insecticides, unique peptidic juvenoids stand out as being highly potent yet exquisitely selective to a specific family of true bugs. Their mode of action is unknown. Here we demonstrate that, like established JH receptor agonists, peptidic juvenoids act upon the JHR Met to halt metamorphosis in larvae of the linden bug, . Peptidic juvenoids induced ligand-dependent dimerization between Met and Tai proteins from but, consistent with their selectivity, not from other insects. A cell-based split-luciferase system revealed that the Met-Tai complex assembled within minutes of agonist presence. To explore the potential of juvenoid peptides, we synthesized 120 new derivatives and tested them in Met-Tai interaction assays. While many substituents led to loss of activity, improved derivatives active at sub-nanomolar range outperformed hitherto existing peptidic and classical juvenoids including fenoxycarb. Their potency in inducing Met-Tai interaction corresponded with the capacity to block metamorphosis in larvae and to stimulate oogenesis in reproductively arrested adult females. Molecular modeling demonstrated that the high potency correlates with high affinity. This is a result of malleability of the ligand-binding pocket of Met that allows larger peptidic ligands to maximize their contact surface. Our data establish peptidic juvenoids as highly potent and species-selective novel JHR agonists.
保幼激素（JH）控制昆虫的变态和繁殖。JH 通过由对灭幼脲敏感（Met）和泰螨（Tai）蛋白组成的受体复合物起作用，诱导特定基因的转录。在化学性质不同的合成 JH 类似物（保幼激素类似物）中，有些可作为杀虫剂，独特的肽类保幼激素因其高度有效且对特定的真螨科昆虫具有极高的选择性而脱颖而出。它们的作用机制尚不清楚。在这里，我们证明了肽类保幼激素与已建立的 JH 受体激动剂一样，作用于 JHR Met，阻止悬铃木象鼻虫幼虫的变态。肽类保幼激素诱导 Met 和 Tai 蛋白从 中发生配体依赖性二聚化，但与它们的选择性一致，不会从其他昆虫中发生。基于细胞的分裂萤光素酶系统显示，Met-Tai 复合物在激动剂存在的几分钟内组装。为了探索保幼激素肽的潜力，我们合成了 120 种新的衍生物，并在 Met-Tai 相互作用测定中对它们进行了测试。虽然许多取代基导致活性丧失，但在亚纳摩尔范围内具有活性的改进衍生物比迄今为止存在的肽类和经典保幼激素，包括 fenoxycarb，表现更好。它们在诱导 Met-Tai 相互作用的效力与在 幼虫中阻断变态以及在生殖性停滞的成年雌性中刺激卵发生的能力相对应。分子建模表明，高效力与高亲和力相关。这是由于 Met 的配体结合口袋的可变性，允许更大的肽类配体最大限度地提高它们的接触表面。我们的数据将肽类保幼激素确立为高度有效和具有物种选择性的新型 JHR 激动剂。
