GTP Is Required for the Microtubule Catastrophe-Inducing Activity of MAP200, a Tobacco Homolog of XMAP215
GTP Is Required for the Microtubule Catastrophe-Inducing Activity of MAP200, a Tobacco Homolog of XMAP215
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DOI：
10.1104/pp.109.144303
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发表时间：
2009-12-01
期刊：
影响因子：
7.4
通讯作者：
Sonobe, Seiji
中科院分区：
文献类型：
--
作者：
Hamada, Takahiro;Itoh, Tomohiko J.;Sonobe, Seiji
微管相关蛋白215（MAP215）家族在真核生物中广泛保守，可增强微管动态不稳定性。研究最广泛的家族成员，非洲爪蟾XMAP 215，据报道，以提高装配和拆卸参数，虽然一个蛋白质可以发挥这些明显矛盾的效果的机制还没有得到澄清。在这里，我们分析了活性的植物MAP215同源物，烟草（烟草）MAP200微管行为在体外。我们发现，像XMAP215，MAP200促进组装和拆卸参数，包括微管生长速率和灾难频率。当MAP200加入到微管蛋白和紫杉醇中时，惊人的长螺旋结构形成。当GDP部分取代GTP时，MAP200对灾难频率的增加被强烈减弱，即使这种替代在没有MAP200的情况下刺激灾难。这意味着MAP200通过一个特定的、需要GTP的途径诱导灾难。我们推测，在MAP200的存在下，一个灾难倾向的微管晶格形式偶尔伸长，但不相邻的原丝进行横向接触。
Widely conserved among eukaryotes, the microtubule-associated protein 215 (MAP215) family enhances microtubule dynamic instability. The family member studied most extensively, Xenopus laevis XMAP215, has been reported to enhance both assembly and disassembly parameters, although the mechanism whereby one protein can exert these apparently contradictory effects has not been clarified. Here, we analyze the activity of a plant MAP215 homolog, tobacco (Nicotiana tabacum) MAP200 on microtubule behavior in vitro. We show that, like XMAP215, MAP200 promotes both assembly and disassembly parameters, including microtubule growth rate and catastrophe frequency. When MAP200 is added to tubulin and taxol, strikingly long-coiled structures form. When GDP partially replaces GTP, the increase of catastrophe frequency by MAP200 is strongly diminished, even though this replacement stimulates catastrophe in the absence of MAP200. This implies that MAP200 induces catastrophes by a specific, GTP-requiring pathway. We hypothesize that, in the presence of MAP200, a catastrophe-prone microtubule lattice forms occasionally when elongated but nonadjacent protofilaments make lateral contacts.