BACKGROUND The c-Jun N-terminal kinases (JNKs), members of the mitogen-activated protein kinase (MAPK) family, engage in diverse cellular responses to signals produced under normal development and stress conditions. In Drosophila, only one JNK member is present, whereas ten isoforms from three JNK genes (JNK1, 2, and 3) are present in mammalian cells. To date, several mammalian JNK structures have been determined, however, there has been no report of any insect JNK structure. RESULTS We report the first structure of JNK from Drosophila melanogaster (DJNK). The crystal structure of the unphosphorylated form of DJNK complexed with adenylyl imidodiphosphate (AMP-PNP) has been solved at 1.79 Å resolution. The fold and topology of DJNK are similar to those of mammalian JNK isoforms, demonstrating their evolutionarily conserved structures and functions. Structural comparisons of DJNK and the closely related mammalian JNKs also allow identification of putative catalytic residues, substrate-binding sites and conformational alterations upon docking interaction with Drosophila scaffold proteins. CONCLUSIONS The DJNK structure reveals common features with those of the mammalian JNK isoforms, thereby allowing the mapping of putative catalytic and substrate binding sites. Additionally, structural changes upon peptide binding could be predicted based on the comparison with the closely-related JNK3 structure in complex with pepJIP1. This is the first structure of insect JNK reported to date, and will provide a platform for future mutational studies in Drosophila to ascertain the functional role of insect JNK.

中文翻译：

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果蝇的JNK的晶体结构揭示了与哺乳动物JNK蛋白的进化保守拓扑。

背景技术有丝分裂原活化的蛋白激酶（MAPK）家族的成员c-Jun N-末端激酶（JNK），参与在正常发育和应激条件下产生的信号的多种细胞应答。在果蝇中，仅存在一个JNK成员，而哺乳动物细胞中存在来自三个JNK基因（JNK1、2和3）的十个同工型。迄今为止，已经确定了几种哺乳动物的JNK结构，但是，没有任何昆虫JNK结构的报道。结果我们报道了果蝇（Drosophila melanogaster，DJNK）的JNK的第一个结构。DJNK的非磷酸化形式与腺苷酰亚胺二磷酸酯（AMP-PNP）络合的晶体结构已在1.79Å分辨率下得到解析。DJNK的折叠和拓扑结构与哺乳动物JNK同工型相似，证明了它们在进化上的保守结构和功能。DJNK和密切相关的哺乳动物JNK的结构比较还可以确定与果蝇支架蛋白对接相互作用时推定的催化残基，底物结合位点和构象变化。结论DJNK结构揭示了与哺乳动物JNK同工型的共同特征，从而允许推定的催化和底物结合位点作图。另外，基于与与pepJIP1复合的紧密相关的JNK3结构的比较，可以预测肽结合后的结构变化。这是迄今报道的昆虫JNK的第一个结构，它将为果蝇今后的突变研究提供一个平台，以确定昆虫JNK的功能。