Institut Pasteur, Unité de Biologie des Interactions Cellulaires, Paris, France; CNRS URA 2582, Paris, France.
Cell Microbiol. 2013 Dec;15(12):2064-79. doi: 10.1111/cmi.12171. Epub 2013 Aug 7.
Chlamydia are obligate intracellular pathogens. Upon contact with the host, they use type III secretion to deliver proteins into the cell, thereby triggering actin-dependent entry and establishing the infection. We observed that Chlamydia caviae elicited a local and transient accumulation of ubiquitinated proteins at the entry sites, which disappeared within 20 min. We investigated the mechanism for the rapid clearance of ubiquitin. We showed that the OTU-like domain containing protein CCA00261, predicted to have deubiquitinase activity, was detected in infectious particles and was a type III secretion effector. This protein is present in several Chlamydia strains, including the human pathogen Chlamydia pneumoniae, and we further designate it as ChlaOTU. We demonstrated that ChlaOTU bound ubiquitin and NDP52, and we mapped these interactions to distinct domains. NDP52 was recruited to Chlamydia entry sites and was dispensable for infection and for bacterial growth. ChlaOTU functioned as a deubiquitinase in vitro. Heterologousexpression of ChlaOTU reduced ubiquitin accumulation at the entry sites, while a catalytic mutant of the deubiquitinase activity had the opposite effect. Altogether, we have identified a novel secreted protein of chlamydiae. ChlaOTU targets both ubiquitin and NDP52 and likely participates in the clearance of ubiquitin at the invasion sites.
衣原体是专性细胞内病原体。在与宿主接触后，它们利用 III 型分泌系统将蛋白质输送到细胞内，从而引发依赖肌动蛋白的进入并建立感染。我们观察到，豚鼠衣原体在进入部位引发了局部和短暂的泛素化蛋白积累，这些积累在 20 分钟内消失。我们研究了快速清除泛素的机制。我们表明，OTU 样结构域包含蛋白 CCA00261（预测具有去泛素化酶活性）存在于感染性颗粒中，是 III 型分泌效应物。该蛋白存在于几种衣原体菌株中，包括人类病原体肺炎衣原体，我们进一步将其命名为 ChlaOTU。我们证明 ChlaOTU 结合泛素和 NDP52，并将这些相互作用映射到不同的结构域。NDP52 被募集到衣原体进入部位，对于感染和细菌生长是可有可无的。ChlaOTU 在体外具有去泛素化酶功能。ChlaOTU 的异源表达减少了进入部位的泛素积累，而去泛素化酶活性的催化突变体则产生相反的效果。总之，我们已经确定了一种新型的衣原体分泌蛋白。ChlaOTU 靶向泛素和 NDP52，并可能参与入侵部位泛素的清除。
