Engineered Myosin VI Motors Reveal Minimal Structural Determinants of Directionality and Processivity
Engineered Myosin VI Motors Reveal Minimal Structural Determinants of Directionality and Processivity
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DOI：
10.1016/j.jmb.2009.07.046
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发表时间：
2009-10-02
影响因子：
5.6
通讯作者：
Bryant, Zev
中科院分区：
文献类型：
--
作者：
Liao, Jung-Chi;Elting, Mary Williard;Bryant, Zev
肌球蛋白具有反映一系列细胞作用的不同机械性质。一个主要的挑战是了解从一个共同的电机核心产生新功能的结构基础。肌球蛋白VI（M6）是专门为进行性运动的（-）结束肌动蛋白丝。我们已经使用工程M6电机测试和完善（-）端方向性的“重定向动力冲程”模型，并探索对步进的结构要求知之甚少。在晶体结构和分子建模的指导下，我们在几个位置将人工杠杆臂融合到M6的催化头部，保留不同量的天然结构。我们发现，18个残基的α-螺旋插入物足以逆转马达的方向性，而不需要任何钙调蛋白轻链。此外，我们观察到强大的步进电机与人工杠杆臂，表明，持续性可以出现没有优化杠杆臂组成或力学。(C)2009爱思唯尔有限公司保留所有权利。
Myosins have diverse mechanical properties reflecting a range of cellular roles. A major challenge is to understand the structural basis for generating novel functions from a common motor core. Myosin VI (M6) is specialized for processive motion toward the (-) end of actin filaments. We have used engineered M6 motors to test and refine the "redirected power stroke" model for (-) end directionality and to explore poorly understood structural requirements for processive stepping. Guided by crystal structures and molecular modeling, we fused artificial lever arms to the catalytic head of M6 at several positions, retaining varying amounts of native structure. We found that an 18-residue alpha-helical insert is sufficient to reverse the directionality of the motor, with no requirement for any calmodulin light chains. Further, we observed robust processive stepping of motors with artificial lever arms, demonstrating that processivity can arise without optimizing lever arm composition or mechanics. (C) 2009 Elsevier Ltd. All rights reserved.