Chlamydia trachomatis Tarp Harbors Distinct G and F Actin Binding Domains That Bundle Actin Filaments
Chlamydia trachomatis Tarp Harbors Distinct G and F Actin Binding Domains That Bundle Actin Filaments
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DOI：
10.1128/jb.01768-12
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发表时间：
2013-02-01
影响因子：
3.2
通讯作者：
Jewett, Travis J.
中科院分区：
文献类型：
--
作者：
Jiwani, Shahanawaz;Alvarado, Stephenie;Jewett, Travis J.
所有种类的衣原体都经历了一个独特的发育周期，在细胞外和细胞内环境之间过渡，需要有能力入侵新的细胞才能传播。一种名为Tarp的衣原体蛋白已被证明在体外能使肌动蛋白成核，并与细菌进入人类细胞有关。异位表达的增强型绿色荧光蛋白(EGFP)-TARP的共定位研究表明，肌动蛋白细丝募集仅限于效应器蛋白的C末端一半。肌动蛋白细丝可能通过肌动蛋白结合的α螺旋与Tarp结合，这也是体外肌动蛋白成核所必需的，但这还没有被研究过。肺炎支原体、鼠疫支原体和豚鼠支原体的TARP同源物的肌动蛋白结合区在1-4个之间，位于蛋白的C末端，而沙眼衣原体血清L2只有一个特征结构域。在这项工作中，我们研究了结构域特定突变对肌动蛋白细丝与EGFP-Tarp共定位的影响。我们现在证明，肌动蛋白细丝与Tarp的共存依赖于两个新的F-肌动蛋白结合域，这两个结构域赋予Tarp效应器肌动蛋白捆绑活性。此外，Tarp介导的肌动蛋白捆绑不需要肌动蛋白成核，因为在肌动蛋白成核缺陷的突变Tarp蛋白中观察到了捆绑肌动蛋白细丝的能力。这些数据提供了沙眼衣原体进入宿主细胞所需的复杂细胞骨架重排的分子洞察力。
All species of Chlamydia undergo a unique developmental cycle that transitions between extracellular and intracellular environments and requires the capacity to invade new cells for dissemination. A chlamydial protein called Tarp has been shown to nucleate actin in vitro and is implicated in bacterial entry into human cells. Colocalization studies of ectopically expressed enhanced green fluorescent protein (EGFP)-Tarp indicate that actin filament recruitment is restricted to the C-terminal half of the effector protein. Actin filaments are presumably associated with Tarp via an actin binding alpha helix that is also required for actin nucleation in vitro, but this has not been investigated. Tarp orthologs from C. pneumoniae, C. muridarum, and C. caviae harbor between 1 and 4 actin binding domains located in the C-terminal half of the protein, but C. trachomatis serovar L2 has only one characterized domain. In this work, we examined the effects of domain-specific mutations on actin filament colocalization with EGFP-Tarp. We now demonstrate that actin filament colocalization with Tarp is dependent on two novel F-actin binding domains that endow the Tarp effector with actin-bundling activity. Furthermore, Tarp-mediated actin bundling did not require actin nucleation, as the ability to bundle actin filaments was observed in mutant Tarp proteins deficient in actin nucleation. These data shed molecular insight on the complex cytoskeletal rearrangements required for C. trachomatis entry into host cells.