Sivabalasarma Shamphavi, Wetzel Hanna, Nußbaum Phillip, van der Does Chris, Beeby Morgan, Albers Sonja-Verena
Molecular Biology of Archaea, Institute of Biology II, Faculty of Biology, University of Freiburg, Freiburg, Germany.
Spemann Graduate School of Biology and Medicine, University of Freiburg, Freiburg, Germany.
Front Microbiol. 2021 Jan 13;11:612239. doi: 10.3389/fmicb.2020.612239. eCollection 2020.
Halophilic archaea have been proposed to exchange DNA and proteins using a fusion-based mating mechanism. Scanning electron microscopy previously suggested that mating involves an intermediate state, where cells are connected by an intercellular bridge. To better understand this process, we used electron cryo-tomography (cryoET) and fluorescence microscopy to visualize cells forming these intercellular bridges. CryoET showed that the observed bridges were enveloped by an surface layer (S-layer) and connected mating cells via a continuous cytoplasm. Macromolecular complexes like ribosomes and unknown thin filamentous helical structures were visualized in the cytoplasm inside the bridges, demonstrating that these bridges can facilitate exchange of cellular components. We followed formation of a cell-cell bridge by fluorescence time-lapse microscopy between cells at a distance of 1.5 μm. These results shed light on the process of haloarchaeal mating and highlight further mechanistic questions.
嗜盐古菌被认为通过基于融合的交配机制来交换DNA和蛋白质。扫描电子显微镜先前表明交配涉及一种中间状态，即细胞通过细胞间桥相连。为了更好地理解这一过程，我们使用电子冷冻断层扫描（cryoET）和荧光显微镜来观察形成这些细胞间桥的细胞。冷冻电镜显示，观察到的桥被表层（S层）包裹，并通过连续的细胞质连接交配细胞。在桥内的细胞质中可以看到核糖体等大分子复合物和未知的细丝状螺旋结构，这表明这些桥可以促进细胞成分的交换。我们通过荧光延时显微镜观察了相距1.5μm的细胞之间细胞间桥的形成。这些结果揭示了嗜盐古菌交配的过程，并突出了进一步的机制问题。
