ANOMALOUS SIGNAL OF SULFUR AS TOOL FOR SOLVING PROTEIN CRYSTAL STRUCTURES?

本项目侧重于一些结构性决定因素 负责调节肌动蛋白的组装属性 细胞骨架和这些活动的体内后果。其中之一 肌动蛋白细丝组装的主要特征 目前所了解的是三磷酸腺苷水解酶作用的机制 肌动蛋白聚合。在X9B，我们现在已经获得了高分辨率 酵母肌动蛋白镁-三磷酸腺苷和镁-腺苷二磷酸形成的数据 网柄网柄菌肌动蛋白。酵母结构在1.9E处明显细化 显示了腺嘌呤核苷酸和八面体配位。 镁离子，以及定位为充当 攻击亲核分子。此外，广泛的水网 在肌动蛋白单体的大裂隙中发现了分子 可能在调控构象重排中起重要作用 发生在细丝伸长时。这些结构将为 首次允许肌动蛋白催化的ATP水解被处理为 真正的酶反应。

This project focuses on a number of structural determinants responsible for regulating the assembly properties of the actin cytoskeleton and the in vivo consequences of these activities. One of the principle features of actin filament assembly that is not currently understood is the mechanism by which ATP hydrolysis effects actin polymerization. At X9B, we have now obtained high resolution data of Mg-ATP yeast actin and both the Mg-ATP and Mg-ADP forms of Dictyostelium actin. The yeast structure refined at 1.9E clearly shows the adenine nucleotide and the octahedral coordination of the magnesium ion, as well as a water molecule positioned to act as the attacking nucleophile. Furthermore, an extensive network of water molecules is revealed in the large cleft of the actin monomer that might be important in modulating the conformational rearrangements that occur upon filament elongation. These structures will for the first time allow for actin catalyzed ATP hydrolysis to be treated a true enzymatic reaction.