Cyclostreptin binds covalently to microtubule pores and lumenal taxoid binding sites
Cyclostreptin binds covalently to microtubule pores and lumenal taxoid binding sites
复制标题
DOI：
10.1038/nchembio853
复制
发表时间：
2007-02-01
影响因子：
14.8
通讯作者：
Diaz, J. Fernando
中科院分区：
文献类型：
--
作者：
Buey, Ruben M.;Calvo, Enrique;Diaz, J. Fernando
链霉菌(Streptomyces sp.)的天然产物环链素(Cyclstreptin，1)。9885，不可逆地稳定细胞微管，导致细胞周期停滞，逃避肿瘤细胞株P-糖蛋白介导的耐药性，并有效地抑制紫杉醇与微管的结合，但仅微弱地诱导微管组装。在试图理解这一悖论的过程中，我们观察到合成的环链素与微管蛋白的不可逆结合。这是因为在细胞微管和由纯化的微管蛋白形成的微管中形成了与β-微管蛋白的共价交联物，总化学计量比为1：1，分布在Thr220(微管壁中孔的外表面)和Asn228(在管腔紫杉醇部位)之间。未聚合的微管蛋白仅在Thr220处标记。因此，β-微管蛋白的孔区是一个未被描述的结合部位，它(I)阐明了紫杉类部位化合物到达动力学上不利的管腔部位的机制，以及(Ii)解释了紫杉类部位的药物如何诱导二聚体和寡聚体微管蛋白形成微管。
Cyclostreptin ( 1), a natural product from Streptomyces sp. 9885, irreversibly stabilizes cellular microtubules, causes cell cycle arrest, evades drug resistance mediated by P- glycoprotein in a tumor cell line and potently inhibits paclitaxel binding to microtubules, yet it only weakly induces tubulin assembly. In trying to understand this paradox, we observed irreversible binding of synthetic cyclostreptin to tubulin. This results from formation of covalent crosslinks to beta- tubulin in cellular microtubules and microtubules formed from purified tubulin in a 1: 1 total stoichiometry distributed between Thr220 ( at the outer surface of a pore in the microtubule wall) and Asn228 ( at the lumenal paclitaxel site). Unpolymerized tubulin was only labeled at Thr220. Thus, the pore region of beta- tubulin is an undescribed binding site that ( i) elucidates the mechanism by which taxoid-site compounds reach the kinetically unfavorable lumenal site and ( ii) explains how taxoid-site drugs induce microtubule formation from dimeric and oligomeric tubulin.