The Positively Charged Region of the Myosin IIC Non-helical Tailpiece Promotes Filament Assembly
The Positively Charged Region of the Myosin IIC Non-helical Tailpiece Promotes Filament Assembly
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DOI：
10.1074/jbc.m109.049221
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发表时间：
2010-03-05
影响因子：
4.8
通讯作者：
Ravid, Shoshana
中科院分区：
文献类型：
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作者：
Ronen, Daniel;Rosenberg, Masha M.;Ravid, Shoshana
运动蛋白，非肌球蛋白II (NMII)，必须经过动态寡聚成细丝参与细胞过程，如细胞迁移和细胞分裂。一个小的非螺旋区域在长螺旋区（尾片）的尾部是所有动态组装肌球蛋白II蛋白的共同特征。在本研究中，我们探讨了尾片在NMII-C自组装中的作用。通过圆二色性和核磁共振实验，我们发现尾片是天然展开的，并被分成两个电荷相反的区域。带正电的区域（Tailpiece(1946-1967)）从残基1946开始，在其N端从传统的盘绕式末端脯氨酸（Tailpiece(1953-1967)）延长了7个氨基酸。拉下和沉降试验表明，阳性尾片（1946-1967）与组装不合格的NMII-C片段结合，诱导纤维组装。负区，残基1968-2000，负责NMII的准晶形态，这是由嵌合体确定的，其中负区在NMII异构体之间交换。正、负肽混合对正肽结合和诱导纤维组装的能力没有影响。该研究为NMII-C结构紊乱的尾部在将NMII-C的寡聚平衡转向细丝组装和决定其形态中的作用提供了分子视角。
The motor protein, non-muscle myosin II (NMII), must undergo dynamic oligomerization into filaments to participate in cellular processes such as cell migration and cytokinesis. A small non-helical region at the tail of the long coiled-coil region (tailpiece) is a common feature of all dynamically assembling myosin II proteins. In this study, we investigated the role of the tailpiece in NMII-C self-assembly. We show that the tailpiece is natively unfolded, as seen by circular dichroism and NMR experiments, and is divided into two regions of opposite charge. The positively charged region (Tailpiece(1946-1967)) starts at residue 1946 and is extended by seven amino acids at its N terminus from the traditional coiled-coil ending proline (Tailpiece(1953-1967)). Pull-down and sedimentation assays showed that the positive Tailpiece(1946-1967) binds to assembly incompetent NMII-C fragments inducing filament assembly. The negative region, residues 1968-2000, is responsible for NMII paracrystal morphology as determined by chimeras in which the negative region was swapped between the NMII isoforms. Mixing the positive and negative peptides had no effect on the ability of the positive peptide to bind and induce filament assembly. This study provides molecular insight into the role of the structurally disordered tailpiece of NMII-C in shifting the oligomeric equilibrium of NMII-C toward filament assembly and determining its morphology.