Department of Physiology and Biophysics, UAMS, Arkansas Childrens Hospital Research Institute, Little Rock, AR, USA.
Cell Microbiol. 2012 May;14(5):656-68. doi: 10.1111/j.1462-5822.2012.01747.x. Epub 2012 Feb 15.
Chlamydia spp. are obligate intracellular bacteria that replicate inside the host cell in a bacterial modified unique compartment called the inclusion. As other intracellular pathogens, chlamydiae exploit host membrane trafficking pathways to prevent lysosomal fusion and to acquire energy and nutrients essential for their survival and replication. The Conserved Oligomeric Golgi (COG) complex is a ubiquitously expressed membrane-associated protein complex that functions in a retrograde intra-Golgi trafficking through associations with coiled-coil tethers, SNAREs, Rabs and COPI proteins. Several COG complex-interacting proteins, including Rab1, Rab6, Rab14 and Syntaxin 6 are implicated in chlamydial development. In this study, we analysed the recruitment of the COG complex and GS15-positive COG complex-dependent vesicles to Chlamydia trachomatis inclusion and their participation in chlamydial growth. Immunofluorescent analysis revealed that both GFP-tagged and endogenous COG complex subunits associated with inclusions in a serovar-independent manner by 8 h post infection and were maintained throughout the entire developmental cycle. Golgi v-SNARE GS15 was associated with inclusions 24 h post infection, but was absent on the mid-cycle (8 h) inclusions, indicating that this Golgi SNARE is directed to inclusions after COG complex recruitment. Silencing of COG8 and GS15 by siRNA significantly decreased infectious yield of chlamydiae. Further, membranous structures likely derived from lysed bacteria were observed inside inclusions by electron microscopy in cells depleted of COG8 or GS15. Our results showed that C. trachomatis hijacks the COG complex to redirect the population of Golgi-derived retrograde vesicles to inclusions. These vesicles likely deliver nutrients that are required for bacterial development and replication.
衣原体属是专性细胞内细菌，在宿主细胞内的一个称为包涵体的细菌修饰的独特隔室中复制。与其他细胞内病原体一样，衣原体利用宿主膜运输途径来防止溶酶体融合，并获取对其生存和复制至关重要的能量和营养物质。保守的寡聚高尔基体 (COG) 复合物是一种普遍表达的膜相关蛋白复合物，通过与卷曲螺旋系绳、SNAREs、Rabs 和 COPI 蛋白的关联，在逆行高尔基体内运输中发挥作用。几种与 COG 复合物相互作用的蛋白质，包括 Rab1、Rab6、Rab14 和 Syntaxin 6，都与衣原体的发育有关。在这项研究中，我们分析了 COG 复合物和 GS15 阳性 COG 复合物依赖性囊泡向沙眼衣原体包涵体的募集及其在衣原体生长中的参与。免疫荧光分析显示，GFP 标记的和内源性 COG 复合物亚基在感染后 8 小时以血清型独立的方式与包涵体相关，并在整个发育周期中保持不变。高尔基 v-SNARE GS15 在感染后 24 小时与包涵体相关，但在中期（8 小时）包涵体中不存在，表明这种高尔基 SNARE 在 COG 复合物募集后被定向到包涵体。siRNA 沉默 COG8 和 GS15 显著降低了衣原体的感染性产量。此外，在耗尽 COG8 或 GS15 的细胞中，通过电子显微镜观察到包涵体内可能来源于裂解细菌的膜状结构。我们的研究结果表明，沙眼衣原体劫持 COG 复合物将高尔基体衍生的逆行囊泡的群体重新定向到包涵体。这些囊泡可能运送细菌发育和复制所需的营养物质。
