Biomolecular Research Unit, National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba, Ibaraki 305-8602, Japan.
Sci Rep. 2011;1:133. doi: 10.1038/srep00133. Epub 2011 Oct 28.
Juvenile hormone (JH) plays crucial roles in many aspects of the insect life. All the JH actions are initiated by transport of JH in the hemolymph as a complex with JH-binding protein (JHBP) to target tissues. Here, we report structural mechanism of JH delivery by JHBP based upon the crystal and solution structures of apo and JH-bound JHBP. In solution, apo-JHBP exists in equilibrium of multiple conformations with different orientations of the gate helix for the hormone-binding pocket ranging from closed to open forms. JH-binding to the gate-open form results in the fully closed JHBP-JH complex structure where the bound JH is completely buried inside the protein. JH-bound JHBP opens the gate helix to release the bound hormone likely by sensing the less polar environment at the membrane surface of target cells. This is the first report that provides structural insight into JH signaling.
保幼激素（JH）在昆虫生活的许多方面发挥着至关重要的作用。JH 的所有作用都是通过将 JH 与 JH 结合蛋白（JHBP）一起作为复合物在血液中运输到靶组织而启动的。在这里，我们根据 apo 和 JH 结合的 JHBP 的晶体和溶液结构，报告了 JHBP 传递 JH 的结构机制。在溶液中，apo-JHBP 存在于多种构象的平衡中，激素结合口袋的门螺旋的方向从关闭到打开形式不等。JH 与打开门的形式结合，导致完全关闭的 JHBP-JH 复合物结构，其中结合的 JH 完全被包裹在蛋白质内部。JH 结合的 JHBP 打开门螺旋以释放结合的激素，可能是通过感知靶细胞细胞膜表面的非极性环境。这是首次提供关于 JH 信号的结构见解的报告。
