Lee Jennifer K, Enciso Germán A, Boassa Daniela, Chander Christopher N, Lou Tracy H, Pairawan Sean S, Guo Melody C, Wan Frederic Y M, Ellisman Mark H, Sütterlin Christine, Tan Ming
Department of Developmental and Cell Biology, University of California, Irvine, CA, 92697-2300, USA.
Department of Mathematics, University of California, Irvine, CA, 92697-3875, USA.
Nat Commun. 2018 Jan 3;9(1):45. doi: 10.1038/s41467-017-02432-0.
Chlamydia trachomatis is the most common cause of bacterial sexually transmitted infection. It produces an unusual intracellular infection in which a vegetative form, called the reticulate body (RB), replicates and then converts into an elementary body (EB), which is the infectious form. Here we use quantitative three-dimensional electron microscopy (3D EM) to show that C. trachomatis RBs divide by binary fission and undergo a sixfold reduction in size as the population expands. Conversion only occurs after at least six rounds of replication, and correlates with smaller RB size. These results suggest that RBs only convert into EBs below a size threshold, reached by repeatedly dividing before doubling in size. A stochastic mathematical model shows how replication-dependent RB size reduction produces delayed and asynchronous conversion, which are hallmarks of the Chlamydia developmental cycle. Our findings support a model in which RB size controls the timing of RB-to-EB conversion without the need for an external signal.
沙眼衣原体是细菌性性传播感染最常见的病因。它会引发一种不同寻常的细胞内感染，在这种感染中，一种被称为网状体（RB）的营养形式进行复制，然后转变为原体（EB），原体是具有传染性的形式。在此，我们使用定量三维电子显微镜（3D EM）来表明，沙眼衣原体网状体通过二分裂进行分裂，并且随着群体数量的增加，其大小会减小六倍。只有在至少六轮复制之后才会发生转变，并且这与较小的网状体大小相关。这些结果表明，网状体只有在达到一个大小阈值以下时才会转变为原体，这个大小阈值是通过在大小翻倍之前反复分裂而达到的。一个随机数学模型展示了依赖复制的网状体大小减小如何产生延迟和异步转变，这是衣原体发育周期的特征。我们的研究结果支持这样一种模型，即网状体大小控制着网状体向原体转变的时间，而无需外部信号。
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