Sporulation, bacterial cell envelopes and the origin of life.
Sporulation, bacterial cell envelopes and the origin of life.
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DOI：
10.1038/nrmicro.2016.85
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发表时间：
2016-08
期刊：
影响因子：
--
通讯作者：
Jensen GJ
中科院分区：
文献类型：
--
作者：
Tocheva EI;Ortega DR;Jensen GJ
电子冷冻断层扫描（ECT）能够在接近天然状态下对完整细胞进行3D重建。ECT产生的图像导致了这样的建议，即一个古老的孢子形成样事件引起了双胚层细菌中的第二层膜。产孢单胚层和双胚层细菌细胞的断层扫描图显示了产孢如何导致双胚层细胞的产生。革兰氏阴性和革兰氏阳性细胞壁和纯化球囊的断层扫描表明，它们比以前认为的更密切相关，并支持它们具有共同起源的假设。将细胞包膜结构的分布映射到最近的生命系统发育树上表明，diderm细胞计划，因此引起它的孢子形成事件，必须非常古老。对这个模型的一种解释是，在早期地球的灾难性转变期间，细胞进化可能经历了一个只有孢子存活的瓶颈，这意味着最后一个细菌共同祖先是孢子。
Electron cryotomography (ECT) enables the 3D reconstruction of intact cells in a near-native state. Images produced by ECT have led to the proposal that an ancient sporulation-like event gave rise to the second membrane in diderm bacteria. Tomograms of sporulating monoderm and diderm bacterial cells show how sporulation can lead to the generation of diderm cells. Tomograms of Gram-negative and Gram-positive cell walls and purified sacculi suggest that they are more closely related than previously thought and support the hypothesis that they share a common origin. Mapping the distribution of cell envelope architectures onto a recent phylogenetic tree of life indicates that the diderm cell plan, and therefore the sporulation-like event that gave rise to it, must be very ancient. One explanation for this model is that during the cataclysmic transitions of the early Earth, cellular evolution may have gone through a bottleneck in which only spores survived, which implies that the last bacterial common ancestor was a spore.