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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Identification of cation-binding sites on actin that drive polymerization and modulate bending stiffness
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Identification of cation-binding sites on actin that drive polymerization and modulate bending stiffness

机译:识别肌动蛋白上的阳离子结合位点,以驱动聚合并调节弯曲刚度

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摘要

The assembly of actin monomers into filaments and networks plays vital roles throughout eukaryotic biology, including intracellular transport, cell motility, cell division, determining cellular shape, and providing cells with mechanical strength. The regulation of actin assembly and modulation of filament mechanical properties are critical for proper actin function. It is well established that physiological salt concentrations promote actin assembly and alter the overall bending mechanics of assembled filaments and networks. However, the molecular origins of these salt-dependent effects, particularly if they involve nonspecific ionic strength effects or specific ion-binding interactions, are unknown. Here, we demonstrate that specific cation binding at two discrete sites situated between adjacent subunits along the long-pitch helix drive actin polymerization and determine the filament bending rigidity. We classify the two sites as "polymerization" and "stiffness" sites based on the effects that mutations at the sites have on salt-dependent filament assembly and bending mechanics, respectively. These results establish the existence and location of the cation-binding sites that confer salt dependence to the assembly and mechanics of actin filaments.
机译:肌动蛋白单体组装成细丝和网络在整个真核生物学中起着至关重要的作用,包括细胞内转运,细胞运动,细胞分裂,确定细胞形状并为细胞提供机械强度。肌动蛋白组装的调节和细丝机械性能的调节对于适当的肌动蛋白功能至关重要。公认的是,生理盐浓度促进肌动蛋白组装并改变组装的细丝和网络的整体弯曲力学。然而,尚不清楚这些盐依赖性作用的分子起源,特别是如果它们涉及非特异性离子强度作用或特异性离子结合相互作用时。在这里,我们证明了沿着长节距螺旋位于相邻亚基之间的两个离散位点处的特定阳离子结合能驱动肌动蛋白聚合并确定长丝的弯曲刚度。基于这些位点上的突变分别对盐依赖性长丝装配和弯曲力学的影响,我们将这两个位点分为“聚合”位点和“刚度”位点。这些结果确定了阳离子结合位点的存在和位置,这些位点赋予肌动蛋白丝的组装和力学机理以盐依赖性。

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