Rapid actin monomer-insensitive depolymerization of Listeria actin comet tails by cofilin, coronin, and Aip1.
Rapid actin monomer-insensitive depolymerization of Listeria actin comet tails by cofilin, coronin, and Aip1.
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DOI：
10.1083/jcb.200603149
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发表时间：
2006-10-23
影响因子：
7.8
通讯作者：
Mitchison, Timothy J
中科院分区：
文献类型：
--
作者：
Brieher, William M;Kueh, Hao Yuan;Ballif, Bryan A;Mitchison, Timothy J
尽管细胞中存在高浓度的可聚合G - 肌动蛋白，但肌动蛋白丝仍会迅速解聚。丝切蛋白被认为是促进肌动蛋白解聚的关键调节因子。在这项研究中，我们发现，尽管纯的丝切蛋白能够拆解单核细胞增生李斯特菌的肌动蛋白彗尾，但在存在可聚合肌动蛋白的情况下，它无法有效地拆解彗尾。胸腺提取物也能迅速拆解彗尾，并且当以丝切蛋白浓度进行归一化时，这种反应比纯丝切蛋白更有效。通过生化分级分离，我们鉴定出Aip1和冠蛋白是胸腺提取物中存在的两种蛋白质，它们有助于丝切蛋白介导的单核细胞增生李斯特菌彗尾的拆解。冠蛋白和Aip1共同降低了解拆彗尾所需的丝切蛋白的量，并使得即使在存在可聚合G - 肌动蛋白的情况下，低浓度的丝切蛋白也能使肌动蛋白解聚。丝切蛋白、冠蛋白和Aip1的协同作用应该为理解肌动蛋白丝如何在细胞的某些部位生长而在其他部位收缩提供生化基础。
Actin filaments in cells depolymerize rapidly despite the presence of high concentrations of polymerizable G actin. Cofilin is recognized as a key regulator that promotes actin depolymerization. In this study, we show that although pure cofilin can disassemble Listeria monocytogenes actin comet tails, it cannot efficiently disassemble comet tails in the presence of polymerizable actin. Thymus extracts also rapidly disassemble comet tails, and this reaction is more efficient than pure cofilin when normalized to cofilin concentration. By biochemical fractionation, we identify Aip1 and coronin as two proteins present in thymus extract that facilitate the cofilin-mediated disassembly of Listeria comet tails. Together, coronin and Aip1 lower the amount of cofilin required to disassemble the comet tail and permit even low concentrations of cofilin to depolymerize actin in the presence of polymerizable G actin. The cooperative activities of cofilin, coronin, and Aip1 should provide a biochemical basis for understanding how actin filaments can grow in some places in the cell while shrinking in others.