A new model for binding of kinesin 13 to curved microtubule protofilaments.
A new model for binding of kinesin 13 to curved microtubule protofilaments.
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DOI：
10.1083/jcb.200812052
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发表时间：
2009-04-06
期刊：
影响因子：
--
通讯作者：
Milligan RA
中科院分区：
文献类型：
--
作者：
Mulder AM;Glavis-Bloom A;Moores CA;Wagenbach M;Carragher B;Wordeman L;Milligan RA
运动蛋白利用三磷酸腺苷水解对微管（MTs）做功。大多数运动蛋白沿着MT行走，但第13类运动蛋白却能识别MT末端并解聚MT原丝。我们已经使用电子显微镜（EM）来了解分子相互作用的激酶13执行这些任务。虽然只有激酶蛋白13的运动结构域的结构体与微管蛋白环的每个异二聚体结合，但含有颈和运动结构域的结构体占据交替的结合位点。同样，二聚体全长（FL）蛋白的EM图谱显示出交替位点结合，但仅显示两个马达头中的一个的密度。这些结果表明二聚体驱动蛋白13的第二个头不能进入弯曲的原丝上邻近的结合位点，并且表明仅颈部就足以阻碍进入。此外，与其他构念相比，FL构念促进了环的堆叠。综上所述，这些数据提出了一种激酶13解聚的模型，其中通过将一个激酶13分子结合到相邻的原丝上来提高效率。
Kinesin motor proteins use adenosine triphosphate hydrolysis to do work on microtubules (MTs). Most kinesins walk along the MT, but class 13 kinesins instead uniquely recognize MT ends and depolymerize MT protofilaments. We have used electron microscopy (EM) to understand the molecular interactions by which kinesin 13 performs these tasks. Although a construct of only the motor domain of kinesin 13 binds to every heterodimer of a tubulin ring, a construct containing the neck and the motor domain occupies alternate binding sites. Likewise, EM maps of the dimeric full-length (FL) protein exhibit alternate site binding but reveal density for only one of two motor heads. These results indicate that the second head of dimeric kinesin 13 does not have access to adjacent binding sites on the curved protofilament and suggest that the neck alone is sufficient to obstruct access. Additionally, the FL construct promotes increased stacking of rings compared with other constructs. Together, these data suggest a model for kinesin 13 depolymerization in which increased efficiency is achieved by binding of one kinesin 13 molecule to adjacent protofilaments.
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