Mutations in Desmin's Carboxy-Terminal "Tail" Domain Severely Modify Filament and Network Mechanics
Mutations in Desmin's Carboxy-Terminal "Tail" Domain Severely Modify Filament and Network Mechanics
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DOI：
10.1016/j.jmb.2010.02.024
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发表时间：
2010-04-16
影响因子：
5.6
通讯作者：
Willenbacher, Norbert
中科院分区：
文献类型：
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作者：
Baer, Harald;Schopferer, Michael;Willenbacher, Norbert
编码中间丝蛋白结蛋白的基因的遗传突变已被证明会引起严重的骨骼肌和心肌病。出乎意料的是，一些突变的结蛋白，特别是在非α-螺旋羧基末端结构域（“尾部”）中携带单个氨基酸改变的结蛋白，已被证明在体外和转染的细胞中形成明显正常的丝。因此，尚不清楚这些突变是否会影响细丝的性质。出于这个原因，我们进行了振荡剪切实验与六个不同的结蛋白“尾巴”突变体，以表征网格大小的细丝网络和它们的应变硬化性能。此外，我们已经进行了高频振荡挤压流测量，以确定各自的长丝的弯曲刚度，其特征在于由持久长度l（p）。有趣的是，除了突变体DesR 454 W外，突变体细丝网络的网格尺寸没有改变，突变体DesR 454 W显然没有形成适当的细丝网络。此外，对于“尾”突变体（l（p）= 1.0-2.0 μ m）和野生型结蛋白（l（p）= 1.1 +/-0.5 μ m），弯曲刚度值在相同范围内。然而，大多数研究结蛋白突变体表现出明显减少应变硬化相比，野生型结蛋白和促进非仿射网络变形。因此，我们的结论是，突变的氨基酸影响intramilial架构和胶体相互作用沿着丝在这样一种方式，应用应变的响应显着alternated.In探索的重要性“尾巴”域等细丝网络属性，我们采用了“尾巴”截短的结蛋白。在标准条件下，它形成了延伸的规则细丝，但未能产生应变硬化。因此，这些数据强烈表明，“尾”域是负责有吸引力的顺磁性细丝的相互作用。此外，这些类型的相互作用也可能与患者肌肉中结蛋白细胞骨架的网络特性有关。(C)2010爱思唯尔有限公司版权所有。
Inherited mutations in the gene coding for the intermediate filament protein desmin have been demonstrated to cause severe skeletal and cardiac myopathies. Unexpectedly, some of the mutated desmins, in particular those carrying single amino acid alterations in the non-alpha-helical carboxyterminal domain ("tail"), have been demonstrated to form apparently normal filaments both in vitro and in transfected cells. Thus, it is not clear if filament properties are affected by these mutations at all. For this reason, we performed oscillatory shear experiments with six different desmin "tail" mutants in order to characterize the mesh size of filament networks and their strain stiffening properties. Moreover, we have carried out high-frequency oscillatory squeeze flow measurements to determine the bending stiffness of the respective filaments, characterized by the persistence length l(p). Interestingly, mesh size was not altered for the mutant filament networks, except for the mutant DesR454W, which apparently did not form proper filament networks. Also, the values for bending stiffness were in the same range for both the "tail" mutants (l(p) = 1.0-2.0 mu m) and the wildtype desmin (l(p) = 1.1 +/- 0.5 mu m). However, most investigated desmin mutants exhibited a distinct reduction in strain stiffening compared to wild-type desmin and promoted nonaffine network deformation. Therefore, we conclude that the mutated amino acids affect intrafilamentous architecture and colloidal interactions along the filament in such a way that the response to applied strain is significantly altered.In order to explore the importance of the "tail" domain as such for filament network properties, we employed a "tail"-truncated desmin. Under standard conditions, it formed extended regular filaments, but failed to generate strain stiffening. Hence, these data strongly indicate that the "tail" domain is responsible for attractive filament-filament interactions. Moreover, these types of interactions may also be relevant to the network properties of the desmin cytoskeleton in patient muscle. (C) 2010 Elsevier Ltd. All rights reserved.