Epothilone and paclitaxel: Unexpected differences in promoting the assembly and stabilization of yeast microtubules
Epothilone and paclitaxel: Unexpected differences in promoting the assembly and stabilization of yeast microtubules
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DOI：
10.1021/bi0121611
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发表时间：
2002-03-26
期刊：
影响因子：
2.9
通讯作者：
Himes, RH
中科院分区：
文献类型：
--
作者：
Bode, CJ;Gupta, ML;Himes, RH
紫杉醇（紫杉醇）和埃泊霉素是促进哺乳动物微管蛋白组装和微管稳定的抗有丝分裂药物。epthilones竞争性地抑制了紫杉醇与哺乳动物脑微管蛋白的结合，这表明这两种化合物在微管蛋白中具有共同的结合位点，尽管它们在结构上缺乏相似性。已知紫杉醇不能稳定体外由酿酒酵母微管形成的微管，因此，可以预期epthilones不会影响酵母微管。然而，我们发现埃泊霉素A和B确实能刺激纯化酵母微管蛋白形成微管。此外，epthilone B在体外严重抑制酵母微管的动力学，其方式类似于紫杉醇对哺乳动物微管的影响。我们使用目前描述紫杉醇和埃泊霉素与哺乳动物β -微管蛋白结合的模型来解释为什么紫杉醇明显不能与酵母微管蛋白结合。我们提出，在酵母β -微管蛋白的n端区域和127位的三个氨基酸取代削弱了紫杉醇的3'-苯并胺基与蛋白质的相互作用。这些结果还表明，酵母微管蛋白的诱变可以帮助确定与紫杉醇和埃泊霉素相互作用的位点。
Paclitaxel (Taxol) and the epothilones are antimitotic agents that promote the assembly of mammalian tubulin and stabilization of microtubules. The epothilones competitively inhibit the binding of paclitaxel to mammalian brain tubulin, suggesting that the two types of compounds share a common binding site in tubulin, despite the lack of structural similarities, It is known that paclitaxel does not stabilize microtubules formed in vitro from Saccharomyces cerevisiae tubulin, thus, it would be expected that the epothilones would not affect yeast microtubules. However, we found that epothilone A and B do stimulate the formation of microtubules from purified yeast tubulin. In addition, epothilone B severely dampens the dynamics of yeast microtubules in vitro in a manner similar to the effect of paclitaxel on mammalian microtubules. We used current models describing paclitaxel and epothilone binding to mammalian beta-tubulin to explain why paclitaxel apparently fails to bind to yeast tubulin, We propose that three amino acid substitutions in the N-terminal region and at position 127 in yeast beta-tubulin weaken the interaction of the 3'-benzamido group of paclitaxel with the protein. These results also indicate that mutagenesis of yeast tubulin could help define the sites of interaction with paclitaxel and the epothilones.