The effect of diffusion, depolymerization and nucleation promoting factors on actin gel growth
The effect of diffusion, depolymerization and nucleation promoting factors on actin gel growth
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DOI：
10.1007/s00249-003-0370-3
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发表时间：
2004-07-01
影响因子：
2
通讯作者：
Sykes, C
中科院分区：
文献类型：
--
作者：
Plastino, J;Lelidis, I;Sykes, C
在真核细胞中，局部肌动蛋白聚合能够使质膜变形并推动细胞前进。肌动蛋白丝的解聚和肌动蛋白单体的扩散确保了聚合位点单体的可用性，因此这些过程必须在细胞肌动蛋白动力学中发挥积极作用。在这里，我们揭示了实验证据表明，肌动蛋白凝胶的增长可以限制单体扩散，与理论预测一致。我们研究了肌动蛋白凝胶形成的珠涂有ActA（和ActA片段），负责肌动蛋白为基础的运动单核细胞增生李斯特菌的细菌因子。我们观察到凝胶厚度的饱和度与珠半径的增加，扩散控制的签名。使用肌动蛋白凝胶生长的弹性模型进行数据分析，得出肌动蛋白单体通过凝胶的扩散系数估计为2 × 10（-8）cm（-2）s（-1），比缓冲液中的扩散系数小10倍，与大量细胞骨架中的文献值一致，为我们的模型提供了佐证。肌动蛋白丝的解聚速率和凝胶的弹性模量也进行了评价。此外，我们定性研究不同的肌动蛋白凝胶时产生的ActA片段与VASP或Arp 2/3复合物相互作用。
In eukaryotic cells, localized actin polymerization is able to deform the plasma membrane and push the cell forward. Depolymerization of actin filaments and diffusion of actin monomers ensure the availability of monomers at sites of polymerization, and therefore these processes must play an active role in cellular actin dynamics. Here we reveal experimental evidence that actin gel growth can be limited by monomer diffusion, consistent with theoretical predictions. We study actin gels formed on beads coated with ActA (and ActA fragments), the bacterial factor responsible for actin-based movement of Listeria monocytogenes. We observe a saturation of gel thickness with increasing bead radius, the signature of diffusion control. Data analysis using an elastic model of actin gel growth gives an estimate of 2x10(-8) cm(-2) s(-1) for the diffusion coefficient of actin monomers through the gel, ten times less than in buffer, and in agreement with literature values in bulk cytoskeleton, providing corroboration of our model. The depolymerization rate of actin filaments and the elastic modulus of the gel are also evaluated. Furthermore, we qualitatively examine the different actin gels produced when ActA fragments interact with either VASP or the Arp2/3 complex.