The AtMAP65-1 cross-bridge between microtubules is formed by one dimer.
The AtMAP65-1 cross-bridge between microtubules is formed by one dimer.
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微管之间的 AtMAP65-1 跨桥由一个二聚体形成。
DOI：
10.1093/pcp/pcm059
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发表时间：
2007
影响因子：
4.9
通讯作者：
M. Yuan
中科院分区：
文献类型：
--
作者：
Hua Li;Tonglin Mao;Ziding Zhang;M. Yuan
来自拟南芥的微管相关蛋白AtMAP 65 -1二聚化并在微管之间形成25 nm的交叉桥，但确切的机制尚不清楚。在这里，我们使用AtMAP 65 -1的预测三维结构作为详细分析实际跨桥的基础。折叠识别预测AtMAP 65 -1包含四个卷曲螺旋结构域和一个柔性延伸环。这些卷曲螺旋结构域的长度约为25 nm，表明一个分子可以跨越差距，因此形成反平行重叠二聚体而不是端对端二聚体。然后，我们通过使用AtMAP 65 -1的截断来测试该模型。EDC {[3-（二甲基氨基）丙基]碳二亚胺}交联分析表明AtMAP 65 -1的杆状结构域的N-末端（氨基酸1-339）结合到杆状结构域的C-末端（氨基酸340-494），并且还参与连接交叉桥中的两个反平行蛋白。然而，微管在AtMAP 65 - 1340 -587（氨基酸340-587）或AtMAP 65 - 11 -494（氨基酸1-494）的存在下仍然可以形成束。比较全长AtMAP 65 -1与AtMAP 65 -1 340-587或AtMAP 65 - 11 -494诱导的微管束的冷稳定性，我们得出结论，AtMAP 65 -1 495-587充当柔性延伸环，在AtMAP 65 -1横桥中结合并稳定微管方面起关键作用。
The microtubule-associated protein AtMAP65-1 from Arabidopsis thaliana dimerizes and forms 25 nm cross-bridges between microtubules, but the exact mechanism is unknown. Here, we used the predicted three-dimensional structure of AtMAP65-1 as a basis for analyzing the actual cross-bridging in detail. Fold-recognition predicts that AtMAP65-1 contains four coiled-coil domains and a flexible extended loop. The length of these coiled-coil domains is about 25 nm, suggesting that one molecule could span the gap, hence forming an antiparallel overlapping dimer instead of an end-to-end dimer. We then tested this model by using truncations of AtMAP65-1. EDC {[3-(dimethylamino) propyl] carbodiimide} cross-linking analysis indicated that the N-terminus of the rod domain of AtMAP65-1 (amino acids 1-339) binds to the C-terminus of the rod domain (amino acids 340-494) and also participates in connecting the two antiparallel proteins in the cross-bridge. Nevertheless, microtubules can still form bundles in the presence of AtMAP65-1 340-587 (amino acids 340-587) or AtMAP65-1 1-494 (amino acids 1-494). Comparing the cold stability of microtubule bundles induced by full-length AtMAP65-1 with that of AtMAP65-1 340-587 or AtMAP65-1 1-494, we conclude that AtMAP65-1 495-587 acts as a flexible extended loop, playing a crucial role in binding to and stabilizing microtubules in the AtMAP65-1 cross-bridge.