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首页> 外文期刊>Molecular biology of the cell >Role of GTP hydrolysis in microtubule dynamics: information from a slowly hydrolyzable analogue, GMPCPP.
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Role of GTP hydrolysis in microtubule dynamics: information from a slowly hydrolyzable analogue, GMPCPP.

机译：GTP水解在微管动力学中的作用：来自可缓慢水解的类似物GMPCPP的信息。

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The role of GTP hydrolysis in microtubule dynamics has been reinvestigated using an analogue of GTP, guanylyl-(alpha, beta)-methylene-diphosphonate (GMPCPP). This analogue binds to the tubulin exchangeable nucleotide binding site (E-site) with an affinity four to eightfold lower than GTP and promotes the polymerization of normal microtubules. The polymerization rate of microtubules with GMPCPP-tubulin is very similar to that of GTP-tubulin. However, in contrast to microtubules polymerized with GTP, GMPCPP-microtubules do not depolymerize rapidly after isothermal dilution. The depolymerization rate of GMPCPP-microtubules is 0.1 s-1 compared with 500 s-1 for GDP-microtubules. GMPCPP also completely suppresses dynamic instability. Contrary to previous work, we find that the beta--gamma bond of GMPCPP is hydrolyzed extremely slowly after incorporation into the microtubule lattice, with a rate constant of 4 x 10(-7) s-1. Because GMPCPP hydrolysis is negligible over the course of a polymerization experiment, it can be used to test the role of hydrolysis in microtubule dynamics. Our results provide strong new evidence for the idea that GTP hydrolysis by tubulin is not required for normal polymerization but is essential for depolymerization and thus for dynamic instability. Because GMPCPP strongly promotes spontaneous nucleation of microtubules, we propose that GTP hydrolysis by tubulin also plays the important biological role of inhibiting spontaneous microtubule nucleation.
机译：GTP水解在微管动力学中的作用已使用GTP的类似物鸟苷基（α，β）-亚甲基-二膦酸酯（GMPCPP）重新进行了研究。该类似物以比GTP低四到八倍的亲和力与微管蛋白可交换核苷酸结合位点（E-site）结合，并促进正常微管的聚合。 GMPCPP-微管蛋白与微管的聚合速率与GTP-微管蛋白非常相似。但是，与用GTP聚合的微管相反，GMPCPP-微管在等温稀释后不会迅速解聚。 GMPCPP微管的解聚速率为0.1 s-1，而GDP微管的解聚速率为500 s-1。 GMPCPP还可以完全抑制动态不稳定性。与以前的工作相反，我们发现GMPCPP的β-γ键在掺入微管晶格后水解非常缓慢，速率常数为4 x 10（-7）s-1。由于GMPCPP水解在聚合实验过程中可忽略不计，因此可用于测试水解在微管动力学中的作用。我们的结果为以下观点提供了有力的新证据：微管蛋白水解GTP对于正常聚合不是必需的，但对于解聚和动态不稳定性是必不可少的。因为GMPCPP强烈促进微管的自发成核，所以我们认为微管蛋白水解GTP还在抑制自发性微管成核方面起着重要的生物学作用。

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