Terminal organelle development in the cell wall-less bacterium Mycloplasma pneumoniae
Terminal organelle development in the cell wall-less bacterium Mycloplasma pneumoniae
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DOI：
10.1073/pnas.0608051103
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发表时间：
2006-10-31
影响因子：
11.1
通讯作者：
Krause, Duncan C.
中科院分区：
文献类型：
--
作者：
Hasselbring, Benjamin M.;Jordan, Jarrat L.;Krause, Duncan C.
支原体是无细胞壁的细菌，被认为是已知的最小和最简单的原核生物之一，但包括肺炎支原体在内的几个物种具有非常复杂的细胞组织，突出表现为存在分化的末端细胞器，一种由电子致密核心区分的膜结合细胞延伸。粘附素蛋白特异性定位于末端细胞器，这也是滑行运动的前端。末端细胞器的复制被认为先于细胞分裂，但其复制的机制及其在此过程中的作用都不清楚。在这里，我们使用荧光蛋白融合和时间推移数字成像研究终端细胞器的形成详细的生长培养的M。肺炎。单个细胞停止滑动作为一个新的终端细胞器形成邻近现有的结构，然后迁移远离短暂静止的新生结构。在观察到胞质分裂之前，通常会形成多个末端细胞器。在一个nonmotile突变体的终端细胞器的分离受损，表明在正常的细胞分裂滑行的要求。同时表达两种不同的荧光蛋白融合的细胞的检查建立了它们的外观的相对顺序，并且随着时间的推移荧光图案的变化表明新生的末端细胞器从头起源，而不是从现有的结构。总之，对终末细胞器形成的时空分析使我们对M. pneumoniae细胞分裂和滑行运动在该过程中的作用。
Mycoplasmas are cell wall-less bacteria considered among the smallest and simplest prokaryotes known, and yet several species including Mycoplasma pneumoniae have a remarkably complex cellular organization highlighted by the presence of a differentiated terminal organelle, a membrane-bound cell extension distinguished by an electron-dense core. Adhesin proteins localize specifically to the terminal organelle, which is also the leading end in gliding motility. Duplication of the terminal organelle is thought to precede cell division, but neither the mechanism of its duplication nor its role in this process is understood. Here we used fluorescent protein fusions and time-lapse digital imaging to study terminal organelle formation in detail in growing cultures of M. pneumoniae. Individual cells ceased gliding as a new terminal organelle formed adjacent to an existing structure, which then migrated away from the transiently stationary nascent structure. Multiple terminal organelles often formed before cytokinesis was observed. The separation of terminal organelles was impaired in a nonmotile mutant, indicating a requirement for gliding in normal cell division. Examination of cells expressing two different fluorescent protein fusions concurrently established their relative order of appearance, and changes in the fluorescence pattern overtime suggested that nascent terminal organelles originated de novo rather than from an existing structure. In summary, spatial and temporal analysis of terminal organelle formation has yielded insights into the nature of M. pneumoniae cell division and the role of gliding motility in that process.