A unique mechanism for the processive movement of single-headed myosin-IX
A unique mechanism for the processive movement of single-headed myosin-IX
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DOI：
10.1016/j.bbrc.2006.03.057
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发表时间：
2006-05-19
影响因子：
3.1
通讯作者：
Ikebe, M
中科院分区：
文献类型：
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作者：
Nishikawa, M;Nishikawa, S;Ikebe, M
肌球蛋白-IX虽然是单头结构，但在多分子体外运动试验中却表现出典型的进行性运动特征，这一点一直令人困惑，因为这不能用双头进行性肌球蛋白的手-手机制来解释。在这里，我们使用两种不同的单分子技术显示了肌球蛋白-IX进行性运动的直接证据。使用光学陷阱纳米测量法，我们发现，肌球蛋白-IX需要几个大的（类似于20 nm）的步骤，然后从肌动蛋白丝分离。此外，我们直接可视化单个肌球蛋白IX分子在肌动蛋白丝上移动了几百纳米，而没有从肌动蛋白丝上解离。由于肌球蛋白IX的进行性运动不锚定颈部域，结果表明，颈部倾斜不涉及肌球蛋白IX的进行性运动。我们认为，肌球蛋白IX头部通过在头部的环2区域中的独特的长且带正电荷的插入，像尺蠖一样沿沿着所有肌动蛋白丝向前移动。(c)2006年爱思唯尔公司All rights reserved.
It has been puzzled that in spite of its single-headed structure, myosin-IX shows the typical character of processive motor in multimolecule in vitro motility assay, because this cannot be explained by hand-over-hand mechanism of the two-headed processive myosins. Here, we show direct evidence of the processive movement of rnyosin-IX using two different single molecule techniques. Using optical trap nanometry, we found that rnyosin-IX takes several large (similar to 20 nm) steps before detaching from an actin filament. Furthermore, we directly visualized the single myosin-IX molecules moving on actin filaments for several hundred nanometers without dissociating from actin filament. Since myosin-IX processively moves without anchoring the neck domain, the result suggests that the neck tilting is not involved for the processive movement of myosin-IX. We propose that the rnyosin-IX head moves processively along all actin filament like an inchworm via a unique long and positively charged insertion in the loop 2 region of the head. (c) 2006 Elsevier Inc. All rights reserved.