NUCLEOTIDE DEPENDENT MOVEMENTS OF KINESIN MOTOR DOMAIN: SIMULATED ANNEALING

ATP 结合驱动蛋白运动结构域的结构 相对于已知的预测和构象差异 鉴定出该蛋白质的 ADP 结合形式*，如报告中所述 参考文献[96]。 差异应该归因于 产生力的 ATP 水解。 候选 ATP 驱动蛋白结构是 通过模拟退火，通过放置 ATP 获得 ADP-驱动蛋白晶体结构中的γ-磷酸盐，以及 原子间距离限制。 此类约束的选择是 基于诱变实验，确定 Gly234 是其中之一 γ-磷酸传感残基，以及结构 驱动蛋白与同源 ncd 电机和 G 的比较 蛋白质。 核苷酸依赖性构象的预测 差异揭示了核苷酸之间的变构耦合 口袋和驱动蛋白的微管结合位点。 的相互作用 含有 Gly234 和 Ser202 的 ATP 会触发电机的结构变化 结构域，作为驱动蛋白变构调节剂的核苷酸 微管结合状态。 我们建议在 ATP 存在的情况下 驱动蛋白的推定微管结合区域（L8、L12、L11、α4、 alpha5 和 alpha6) 形成形状互补的面 微管表面。 当 ADP 存在时，微管结合 相对于 ATP 结合形式，面部采用更凸的形状， 降低驱动蛋白与微管的亲和力。

The structure of an ATP-bound kinesin motor domain has been predicted and conformational differences relative to the known ADP-bound form of the protein were identified,* as reported in reference [96]. The differences should be attributed to force-producing ATP hydrolysis. Candidate ATP-kinesin structures were obtained by simulated annealing, by placement of the ATP gamma-phosphate in the crystal structure of ADP-kinesin, and by inter-atomic distance constraints. The choice of such constraints was based on mutagenesis experiments, which identified Gly234 as one of the gamma-phosphate sensing residues, as well as on structural comparison of kinesin with the homologous ncd motor and with G proteins. The prediction of nucleotide-dependent conformational differences reveals an allosteric coupling between the nucleotide pocket and the microtubule binding site of kinesin. Interactions of ATP with Gly234 and Ser202 trigger structural changes in the motor domain, the nucleotide acting as an allosteric modifier of kinesin's microtubule-binding state. We suggest that in the presence of ATP kinesin's putative microtubule binding regions (L8, L12, L11, alpha4, alpha5 and alpha6) form a face complementary in shape to the microtubule surface. In the presence of ADP, the microtubule binding face adopts a more convex shape relative to the ATP-bound form, reducing kinesin's affinity to the microtubule.