Molecular Biology of Archaea, Faculty of Biology, University of Freiburg, Freiburg, Germany.
Cell Biology, Faculty of Biology, University of Freiburg, Freiburg, Germany.
mBio. 2019 May 7;10(3):e00377-19. doi: 10.1128/mBio.00377-19.
Bacteria and archaea exhibit tactical behavior and can move up and down chemical gradients. This tactical behavior relies on a motility structure, which is guided by a chemosensory system. Environmental signals are sensed by membrane-inserted chemosensory receptors that are organized in large ordered arrays. While the cellular positioning of the chemotaxis machinery and that of the flagellum have been studied in detail in bacteria, we have little knowledge about the localization of such macromolecular assemblies in archaea. Although the archaeal motility structure, the archaellum, is fundamentally different from the flagellum, archaea have received the chemosensory machinery from bacteria and have connected this system with the archaellum. Here, we applied a combination of time-lapse imaging and fluorescence and electron microscopy using the model euryarchaeon and found that archaella were specifically present at the cell poles of actively dividing rod-shaped cells. The chemosensory arrays also had a polar preference, but in addition, several smaller arrays moved freely in the lateral membranes. In the stationary phase, rod-shaped cells became round and chemosensory arrays were disassembled. The positioning of archaella and that of chemosensory arrays are not interdependent and likely require an independent form of positioning machinery. This work showed that, in the rod-shaped haloarchaeal cells, the positioning of the archaellum and of the chemosensory arrays is regulated in time and in space. These insights into the cellular organization of suggest the presence of an active mechanism responsible for the positioning of macromolecular protein complexes in archaea. Archaea are ubiquitous single cellular microorganisms that play important ecological roles in nature. The intracellular organization of archaeal cells is among the unresolved mysteries of archaeal biology. With this work, we show that cells of haloarchaea are polarized. The cellular positioning of proteins involved in chemotaxis and motility is spatially and temporally organized in these cells. This suggests the presence of a specific mechanism responsible for the positioning of macromolecular protein complexes in archaea.
细菌和古菌表现出战术行为，可以在化学梯度上上下移动。这种战术行为依赖于一个运动结构，该结构由化学感觉系统引导。环境信号由插入膜中的化学感觉受体感知，这些受体以大的有序阵列组织。虽然细菌中已经详细研究了趋化运动机制和鞭毛的细胞定位，但我们对古菌中这种大分子组装体的定位知之甚少。虽然古菌的运动结构——古菌鞭毛，与鞭毛根本不同，但古菌从细菌中获得了化学感觉机制，并将该系统与古菌鞭毛连接起来。在这里，我们应用了延时成像和荧光及电子显微镜的组合，使用模型广古菌，发现古菌鞭毛专门存在于活跃分裂的杆状细胞的细胞极。化学感觉阵列也有极性偏好，但除此之外，几个较小的阵列在侧膜中自由移动。在停滞期，杆状细胞变成圆形，化学感觉阵列解体。古菌鞭毛和化学感觉阵列的定位不是相互依赖的，可能需要一种独立的定位机制。这项工作表明，在杆状盐杆菌细胞中，古菌鞭毛和化学感觉阵列的定位是时间和空间上受到调节的。这些对的细胞组织的见解表明，存在一种主动机制负责定位古菌中的大分子蛋白复合物。古菌是普遍存在的单细胞微生物，在自然界中发挥着重要的生态作用。古菌细胞的细胞内组织是古菌生物学中尚未解决的谜团之一。通过这项工作，我们表明盐杆菌细胞是极化的。参与趋化和运动的蛋白质的细胞定位在这些细胞中是空间和时间上有组织的。这表明存在一种特定的机制，负责定位古菌中的大分子蛋白复合物。
