Center for Biocrystallographic Research, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznan, Poland.
Department of Crystallography, Faculty of Chemistry, A. Mickiewicz University, Poznan, Poland.
FEBS J. 2018 May;285(10):1907-1922. doi: 10.1111/febs.14455. Epub 2018 Apr 20.
LlPR-10.2B, a Pathogenesis-related class 10 (PR-10) protein from yellow lupine (Lupinus luteus) was crystallized in complex with melatonin, an emerging important plant regulator and antioxidant. The structure reveals two molecules of melatonin bound in the internal cavity of the protein, plus a very well-defined electron density near the cavity entrance, corresponding to an unknown ligand molecule comprised of two flat rings, which is most likely a product of melatonin transformation. In a separate LlPR-10.2B co-crystallization experiment with an equimolar mixture of melatonin and trans-zeatin, which is a cytokinin phytohormone well recognized as a PR-10-binding partner, a quaternary 1 : 1 : 1 : 1 complex was formed, in which one of the melatonin-binding sites has been substituted with trans-zeatin, whereas the binding of melatonin at the second binding site and binding of the unknown ligand are undisturbed. This unusual complex, when compared with the previously described PR-10/trans-zeatin complexes and with the emerging structural information about melatonin binding by PR-10 proteins, provides intriguing insights into the role of PR-10 proteins in phytohormone regulation in plants, especially with the involvement of melatonin, and implicates the PR-10 proteins as low-affinity melatonin binders under the conditions of elevated melatonin concentration.
Atomic coordinates and processed structure factors corresponding to the final models of the LlPR-10.2B/melatonin and LlPR-10.2B/melatonin + trans-zeatin complexes have been deposited with the Protein Data Bank (PDB) under the accession codes 5MXB and 5MXW. The corresponding raw X-ray diffraction images have been deposited in the RepOD Repository at the Interdisciplinary Centre for Mathematical and Computational Modelling (ICM) of the University of Warsaw, Poland, and are available for download with the following Digital Object Identifiers (DOI): https://doi.org/10.18150/repod.9923638 and https://doi.org/10.18150/repod.6621013.
来自黄花羽扇豆（Lupinus luteus）的 PR-10 类 10（PR-10）蛋白 LlPR-10.2B 与褪黑素（一种新兴的重要植物调节剂和抗氧化剂）复合结晶。该结构揭示了两个褪黑素分子结合在蛋白质的内部腔中，加上腔入口附近非常明确的电子密度，对应于空腔入口附近的未知配体分子，该分子由两个扁平环组成，最有可能是褪黑素转化的产物。在与褪黑素和玉米素（一种公认的 PR-10 结合伴侣的细胞分裂素植物激素）等摩尔混合物的单独 LlPR-10.2B 共结晶实验中，形成了一个四元 1:1:1:1 复合物，其中一个褪黑素结合位点被玉米素取代，而第二个结合位点的褪黑素结合和未知配体的结合不受干扰。与先前描述的 PR-10/玉米素复合物以及关于 PR-10 蛋白结合褪黑素的新兴结构信息相比，这种不寻常的复合物提供了关于 PR-10 蛋白在植物激素调节中的作用的有趣见解，特别是涉及褪黑素，并暗示 PR-10 蛋白在褪黑素浓度升高的情况下作为低亲和力褪黑素结合物。
对应于 LlPR-10.2B/褪黑素和 LlPR-10.2B/褪黑素+玉米素复合物最终模型的原子坐标和处理后的结构因子已被存入蛋白质数据银行（PDB），并分配了访问代码 5MXB 和 5MXW。相应的原始 X 射线衍射图像已被存入波兰华沙大学数学与计算建模跨学科中心（ICM）的 RepOD 存储库中，可通过以下数字对象标识符（DOI）下载：https://doi.org/10.18150/repod.9923638 和 https://doi.org/10.18150/repod.6621013。
