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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Motility of ActA protein-coated microspheres driven by actin polyoerization
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Motility of ActA protein-coated microspheres driven by actin polyoerization

机译：肌动蛋白多分子化作用驱动ActA蛋白包被的微球

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摘要

Actin polymerization is required for the gen- eration of motile force at the leading edge of both lamellipodia and filopodia and also at the surface of motile intracellular bacterial pathogens such as Listeria monocytogenes. Local catalysis of actin filament polymerization is accomplished in L. monocytogenes by the bacterial protein ActA. Polystyrene beads coated with purified ActA protein can undergo direc- tional movement in an actin-rich cytoplasmic extract. Thus, the actin polymerization-based motility generated by ActA can be used to move nonbiological cargo, as has been demon- strated for classical motor moleculcs such as kinesin and myosin. Initiation of unidirectional movement of a symmet- rically coated particle is a function of bead size and surface protein density. Small beads (<=0.5 #mu#m in diameter) initiate actin-based motility when local asymmetries are built up by random fluctuations of actin filament density or by thermal motion, demonstrating the inherent ability of the dynamic actin cytoskeleton to spontaneously self-organize into a polar structure capable of generating unidirectional force. Larger beads (up to 2 #mu#m in diameter) can initiate movement only if surface asymmetry is introduced by coating the beads on one hemisphere. This explains why the relatively large L. mono- cytogenes requires polar distribution of ActA on its surface to move.
机译：肌动蛋白聚合是产生运动的动力，需要在lamellipodia和filopodia的前沿以及运动性细胞内细菌病原体（如单核细胞增生李斯特氏菌）的表面产生运动力。肌动蛋白丝聚合的局部催化作用是通过细菌蛋白ActA在单核细胞增生李斯特氏菌中完成的。涂有纯化ActA蛋白的聚苯乙烯珠可以在富含肌动蛋白的细胞质提取物中进行定向运动。因此，ActA产生的基于肌动蛋白聚合的动力可用于移动非生物货物，正如经典动力分子（如驱动蛋白和肌球蛋白）所证明的那样。对称包覆颗粒的单向运动的开始是珠粒大小和表面蛋白密度的函数。当通过肌动蛋白丝密度的随机波动或通过热运动建立局部不对称性时，小珠子（直径<= 0.5＃μm）会启动基于肌动蛋白的运动，这表明动态肌动蛋白细胞骨架自发地自组织的固有能力变成能够产生单向力的极结构。只有通过将磁珠涂覆在一个半球上而引入表面不对称性，较大的磁珠（直径最大为2＃μm）才能启动运动。这解释了为什么相对较大的单核细胞增生李斯特氏菌需要在其表面上移动ActA的极性分布。

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