Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL 32610, USA.
BMC Microbiol. 2013 Aug 7;13:185. doi: 10.1186/1471-2180-13-185.
The developmental cycle of the obligate intracellular pathogen Chlamydia is dependant on the formation of a unique intracellular niche termed the chlamydial inclusion. The inclusion is a membrane bound vacuole derived from host cytoplasmic membrane and is modified significantly by the insertion of chlamydial proteins. A unique property of the inclusion is its propensity for homotypic fusion. The vast majority of cells infected with multiple chlamydial elementary bodies (EBs) contain only a single mature inclusion. The chlamydial protein IncA is required for fusion, however the host process involved are uncharacterized.
Here, through live imaging studies, we determined that the nascent inclusions clustered tightly at the cell microtubule organizing center (MTOC) where they eventually fused to form a single inclusion. We established that factors involved in trafficking were required for efficient fusion as both disruption of the microtubule network and inhibition of microtubule trafficking reduced the efficiency of fusion. Additionally, fusion occurred at multiple sites in the cell and was delayed when the microtubule minus ends were either no longer anchored at a single MTOC or when a cell possessed multiple MTOCs.
The data presented demonstrates that efficient homotypic fusion requires the inclusions to be in close proximity and that this proximity is dependent on chlamydial microtubule trafficking to the minus ends of microtubules.
专性细胞内病原体衣原体的发育周期依赖于一种独特的细胞内小生境的形成，称为衣原体包涵体。包涵体是一种源自宿主细胞质膜的膜结合空泡，通过插入衣原体蛋白而得到显著修饰。包涵体的一个独特特性是其同源融合的倾向。绝大多数感染多个衣原体原体（EB）的细胞仅含有一个成熟的包涵体。衣原体蛋白 IncA 是融合所必需的，但涉及的宿主过程尚未确定。
在这里，通过实时成像研究，我们确定了新形成的包涵体在细胞微管组织中心（MTOC）处紧密聚集，最终融合形成一个包涵体。我们确定了参与运输的因子对于有效融合是必需的，因为微管网络的破坏和微管运输的抑制都降低了融合的效率。此外，融合发生在细胞的多个部位，当微管的负端不再锚定在单个 MTOC 上，或者当一个细胞拥有多个 MTOC 时，融合会被延迟。
所呈现的数据表明，有效的同源融合需要包涵体紧密接近，而这种接近取决于衣原体微管向微管负端的运输。
