THE SPONGISTATINS, POTENTLY CYTOTOXIC INHIBITORS OF TUBULIN POLYMERIZATION, BIND IN A DISTINCT REGION OF THE VINCA DOMAIN
THE SPONGISTATINS, POTENTLY CYTOTOXIC INHIBITORS OF TUBULIN POLYMERIZATION, BIND IN A DISTINCT REGION OF THE VINCA DOMAIN
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DOI：
10.1021/bi00030a009
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发表时间：
1995-08-01
期刊：
影响因子：
2.9
通讯作者：
HAMEL, E
中科院分区：
文献类型：
--
作者：
BAI, RL;TAYLOR, GF;HAMEL, E
高细胞毒性，海绵衍生的，抗有丝分裂的大环内酯聚醚海绵抑素1先前已被证明可以抑制微管组装，长春花碱和GTP与微管蛋白的结合，以及微管蛋白交换位点的GDP的移位。我们现在详细研究了海绵抑素1对[H-3]长春花碱和[H-3]dolastatin 10与微管蛋白结合的抑制作用。我们发现海绵抑素1是两种放射性标记药物与微管蛋白结合的非竞争性抑制剂，与长春新碱与[H-3]长春花碱以及dolastatin 10与[H-3]dolastatin 10的手性异构体形成的竞争性模式形成对比。由于dolastatin 10本身是一种非竞争性的长春花生物碱与微管蛋白结合的抑制剂，这意味着至少有三个不同的结合位点存在于结构复杂和多样的天然产物中，这些产物会相互干扰与微管蛋白的结合和核苷酸交换。与长春花生物碱和肽抗有丝分裂剂（如dolastatin 10）相比，Spongistatin 1不会诱导形成不依赖于gtp的、形态独特的聚合物（“聚合体”）。我们还研究了8种结构上与海绵抑素1密切相关的化合物（海绵抑素2-9）。它们最独特的性质是海绵抑素6和8。尽管这两种化合物作为微管蛋白聚合和[H-3]vinblastine结合抑制剂的活性与海绵抑素1相当，但作为核苷酸交换和[H-3]dolastatin 10结合抑制剂的活性却大大降低。比较了Spongistatins 1和6对dolastatin 10诱导的聚集体形成的影响以及对[K-3]dolastatin 10结合的影响。作为聚集抑制剂，海绵抑素6的活性比海绵抑素1低约4倍，作为dolastatin 10结合抑制剂的活性比海绵抑素1低20倍以上。
The highly cytotoxic, sponge-derived, antimitotic macrolide polyether spongistatin 1 has been previously shown to inhibit microtubule assembly, the binding of vinblastine and GTP to tubulin, and displacement of GDP bound in the exchangeable site of tubulin. We have now examined in detail inhibition by spongistatin 1 of both [H-3]vinblastine and [H-3]dolastatin 10 binding to tubulin, We found spongistatin 1 to be a noncompetitive inhibitor of the binding of both radiolabeled drugs to tubulin, in contrast to competitive patterns obtained with vincristine versus [H-3]viriblastine and with a chiral isomer of dolastatin 10 versus [H-3]dolastatin 10. Since dolastatin 10 is itself a noncompetitive inhibitor of vinca alkaloid binding to tubulin, this implies at least three distinct binding sites for the structurally complex and diverse natural products that interfere with each others binding to tubulin and with nucleotide exchange, Spongistatin 1, in contrast to both vinca alkaloids and peptide antimitotic agents like dolastatin 10, does not induce formation of a GTP-independent, morphologically distinctive polymer (''aggregate''), We also examined eight compounds closely related structurally to spongistatin 1 (spongistatins 2-9). The most distinctive in their properties were spongistatins 6 and 8. These two compounds, despite activity comparable to spongistatin 1 as inhibitors of tubulin polymerization and [H-3]vinblastine binding, had much reduced activity as inhibitors of nucleotide exchange and [H-3]dolastatin 10 binding. Spongistatins 1 and 6 were compared for effects on dolastatin 10-induced aggregate formation in conjunction with effects on [K-3]dolastatin 10 binding. Spongistatin 6 was about 4-fold less active than spongistatin 1 as an inhibitor of aggregation and over 20-fold less active as an inhibitor of dolastatin 10 binding.