Juvenile hormone diol kinase (JHDK) is an important enzyme involved in the juvenile hormone metabolism pathway, which catalyzes the phosphorylation of juvenile hormone diol to form the polar metabolite JH diol phosphate. Here, we reported the first crystal structure of insect JHDK from Bombyx mori, BmJHDK-L2, determined at a resolution of 1.22 Å. The structure of BmJHDK-L2 mainly comprises of eight α-helical segments linked with loops, forming four helix-loop-helix motifs. In these four helix-loop-helix motifs with only one calcium ion bound in the first motif. Circular dichroism spectra indicated that BmJHDK-L2 has strong thermal stability, which is independent of the divalent cation. The structure of BmJHDK-L2 further allowed us to define an ATP-binding site using computational simulation and binding assays, providing a structural basis for development of inhibitor of JHDK. Moreover, the expression profile of BmJHDK-L2 indicated a predominant role in juvenile hormone metabolism in the Malpighian tubules of silkworm. Collectively, these findings expand our knowledge regarding the structural and biochemical features of insect JHDK proteins.

少年激素二醇激酶（JHDK）是一种参与少年激素代谢途径的重要酶，催化少年激素二醇的磷酸化反应，形成极性代谢产物JH二醇磷酸酯。在此，我们报道的昆虫JHDK从第一晶体结构家蚕，家蚕JHDK-L2，在1.22埃的分辨率来确定。Bm JHDK-L2的结构主要由八个与环相连的α-螺旋片段组成，形成四个螺旋-环-螺旋基序。在这四个螺旋-环-螺旋基序中，只有一个钙离子结合在第一个基序中。圆二色性光谱表明，Bm JHDK-L2具有很强的热稳定性，与二价阳离子无关。Bm的结构JHDK-L2进一步允许我们使用计算模拟和结合测定法来定义ATP结合位点，为开发JHDK抑制剂提供了结构基础。此外，Bm JHDK-L2的表达谱表明家蚕的Malpighian小管在幼年激素代谢中起主要作用。总的来说，这些发现扩展了我们对昆虫JHDK蛋白的结构和生化特征的认识。