Adenine Nucleotide-dependent Regulation of Assembly of Bacterial Tubulin-like FtsZ by a Hypermorph of Bacterial Actin-like FtsA
Adenine Nucleotide-dependent Regulation of Assembly of Bacterial Tubulin-like FtsZ by a Hypermorph of Bacterial Actin-like FtsA
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DOI：
10.1074/jbc.m808872200
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发表时间：
2009-05-22
影响因子：
4.8
通讯作者：
Margolin, William
中科院分区：
文献类型：
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作者：
Beuria, Tushar K.;Mullapudi, Srinivas;Margolin, William
细菌中的细胞分裂取决于收缩性 Z 环，它由微管蛋白同源物 FtsZ 以及其他膜相关蛋白（例如 FtsA）的动态聚合物组成，FtsA 是 Z 环膜附着及其随后收缩所需的肌动蛋白同源物。在这里，我们展示了先前表征的超态突变体 FtsA (FtsA*) 在体外部分分解了 FtsZ 聚合物。这种效应严格依赖于 ATP 或 ADP 与 FtsA* 的结合，并且相对于 FtsZ 发生在亚化学计量水平，类似于细胞水平。核苷酸结合的 FtsA* 不影响 FtsZ GTPase 活性或 FtsZ 组装的临界浓度，但能够分解预先形成的 FtsZ 聚合物，表明 FtsA* 作用于 FtsZ 聚合物。对受抑制的 FtsZ 聚合物的显微镜检查揭示了从长直聚合物和聚合物束到主要是短弯曲原丝的转变。这些结果表明，细菌肌动蛋白在被腺嘌呤核苷酸激活时可以改变细菌微管蛋白聚合物的长度分布，类似于肌动蛋白解聚因子/丝切蛋白对F-肌动蛋白的影响。
Cytokinesis in bacteria depends upon the contractile Z ring, which is composed of dynamic polymers of the tubulin homolog FtsZ as well as other membrane-associated proteins such as FtsA, a homolog of actin that is required for membrane attachment of the Z ring and its subsequent constriction. Here we show that a previously characterized hypermorphic mutant FtsA (FtsA*) partially disassembled FtsZ polymers in vitro. This effect was strictly dependent on ATP or ADP binding to FtsA* and occurred at sub-stoichiometric levels relative to FtsZ, similar to cellular levels. Nucleotide-bound FtsA* did not affect FtsZ GTPase activity or the critical concentration for FtsZ assembly but was able to disassemble preformed FtsZ polymers, suggesting that FtsA* acts on FtsZ polymers. Microscopic examination of the inhibited FtsZ polymers revealed a transition from long, straight polymers and polymer bundles to mainly short, curved protofilaments. These results indicate that a bacterial actin, when activated by adenine nucleotides, can modify the length distribution of bacterial tubulin polymers, analogous to the effects of actin-depolymerizing factor/cofilin on F-actin.