Force Generation by Endocytic Actin Patches in Budding Yeast
Force Generation by Endocytic Actin Patches in Budding Yeast
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DOI：
10.1016/j.bpj.2014.02.035
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发表时间：
2014-04-15
影响因子：
3.4
通讯作者：
Bayly, Philip V.
中科院分区：
文献类型：
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作者：
Carlsson, Anders E.;Bayly, Philip V.
在酵母的内吞作用过程中，膜变形是由一系列蛋白质的局部模板化组装驱动的，这些蛋白质包括聚合的肌动蛋白以及产生曲率的包被蛋白，如网格蛋白。肌动蛋白聚合对于成功的内吞作用是必需的，但肌动蛋白聚合产生所需拉力的机制尚不清楚。为了解决这个问题，我们开发了一种模拟方法，其中将蛋白质斑块处的肌动蛋白网络建模为一种活性凝胶。使用有限元方法处理凝胶的变形。我们探究了三种不同类型的驱动内陷的力的作用和相互影响：1）垂直于膜的力，由斑块边缘和中心的肌动蛋白聚合速率差异产生；2）包被蛋白层的固有曲率；3）由肌动球蛋白收缩环产生的平行于膜且使包被蛋白层弯曲的力。我们发现，在对肌动蛋白凝胶生长的停滞应力和肌动蛋白凝胶的剪切模量进行乐观估计的情况下，肌动蛋白聚合能够产生几乎足以克服膨压的力。与其他机制相结合，肌动蛋白聚合能够使力超过临界值。
Membrane deformation during endocytosis in yeast is driven by local, templated assembly of a sequence of proteins including polymerized actin and curvature-generating coat proteins such as clathrin. Actin polymerization is required for successful endocytosis, but it is not known by what mechanisms actin polymerization generates the required pulling forces. To address this issue, we develop a simulation method in which the actin network at the protein patch is modeled as an active gel. The deformation of the gel is treated using a finite-element approach. We explore the effects and interplay of three different types of. force driving invagination: 1), forces perpendicular to the membrane, generated by differences between actin polymerization rates at the edge of the patch and those at the center; 2), the inherent curvature of the coat-protein layer; and 3), forces parallel to the membrane that buckle the coat protein layer, generated by an actomyosin contractile ring. We find that with optimistic estimates for the stall stress of actin gel growth and the shear modulus of the actin gel, actin polymerization can generate almost enough force to Overcome the turgor pressure. In combination with the other mechanisms, actin polymerization can the force over the critical value.