Structural conservation of chemotaxis machinery across Archaea and Bacteria.
Structural conservation of chemotaxis machinery across Archaea and Bacteria.
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跨古细菌和细菌的趋化机制的结构保护。
DOI：
10.1111/1758-2229.12265
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发表时间：
2015-06
影响因子：
3.3
通讯作者：
Jensen GJ
中科院分区：
文献类型：
--
作者：
Briegel A;Ortega DR;Huang AN;Oikonomou CM;Gunsalus RP;Jensen GJ
趋化性使细胞能够感知和响应环境。在细菌中，刺激被化学感受器阵列检测到，化学感受器阵列将信号传递给双组分调节系统。这些阵列采用高度定型的超晶格的形式，其包含由组氨酸激酶和偶联蛋白的环网络化的六方堆积的受体二聚体的三聚体。这种结构在趋化性细菌中以及在膜结合和细胞质阵列之间是保守的，并且产生了信号系统的高度合作的动态性质。在真核生物中不存在的趋化系统也在古细菌中发现，其结构细节仍然没有特征。在这里，我们提供的证据表明，趋化机制是不存在于最后的古细菌的共同祖先，而是在一个波的横向基因转移后，真核生物的分支，但之前的多样化的广古菌。与细菌不同的是，趋化性系统在细菌中主要是垂直进化的，很少有随后成功的横向基因转移事件。通过电子冷冻断层扫描（ECT），我们发现，膜结合和细胞质化学感受器阵列的结构是保守的细菌和大肠杆菌之间，这表明在不同的原核生物的生活方式，这种信号结构的根本重要性。
Chemotaxis allows cells to sense and respond to their environment. In bacteria, stimuli are detected by arrays of chemoreceptors that relay the signal to a two-component regulatory system. These arrays take the form of highly stereotyped super-lattices comprising hexagonally packed trimers-of-receptor-dimers networked by rings of histidine kinase and coupling proteins. This structure is conserved across chemotactic bacteria, and between membrane-bound and cytoplasmic arrays, and gives rise to the highly cooperative, dynamic nature of the signaling system. The chemotaxis system, absent in eukaryotes, is also found in archaea, where its structural details remain uncharacterized. Here we provide evidence that the chemotaxis machinery was not present in the last archaeal common ancestor, but rather was introduced in one of the waves of lateral gene transfer that occurred after the branching of Eukaryota but before the diversification of Euryarchaeota. Unlike in Bacteria, the chemotaxis system then evolved largely vertically in Archaea, with very few subsequent successful lateral gene transfer events. By electron cryotomography (ECT), we find that the structure of both membrane-bound and cytoplasmic chemoreceptor arrays is conserved between Bacteria and Archaea, suggesting the fundamental importance of this signaling architecture across diverse prokaryotic lifestyles.