Coordinated Assembly of the Bacillus anthracis Coat and Exosporium during Bacterial Spore Outer Layer Formation.
Coordinated Assembly of the Bacillus anthracis Coat and Exosporium during Bacterial Spore Outer Layer Formation.
复制标题
细菌孢子外层形成期间，炭疽芽孢杆菌涂层和外孢子的配位组件。
DOI：
10.1128/mbio.01166-18
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发表时间：
2018-11-06
期刊：
影响因子：
6.4
通讯作者：
Driks A
中科院分区：
文献类型：
--
作者：
Boone TJ;Mallozzi M;Nelson A;Thompson B;Khemmani M;Lehmann D;Dunkle A;Hoeprich P;Rasley A;Stewart G;Driks A
这项工作极大地提高了我们对炭疽芽孢杆菌孢子最外层外孢层组装的理解，外孢层包裹着许多细菌种类的孢子，可能在孢子与环境（包括宿主组织）的相互作用中起着重要作用。尽管如此，指导外孢子组装成孢子周围的壳的机制仍然知之甚少。在这项研究中，我们通过鉴定一种新的蛋白质相互作用网络来阐明这些机制，该网络指导组装在发育细胞的特定亚细胞位置启动。我们的研究结果进一步表明，外孢子的存在与否对其他更内层孢子层的组装有重大影响，从而可能解释了炭疽芽孢杆菌和模式生物枯草芽孢杆菌之间孢子组装的长期差异。由芽胞杆菌产生的细菌孢子由同心壳组成，每个壳都有助于孢子的功能。所有物种的孢子都有皮层和被毛，但许多物种的孢子都有额外的外层。炭疽芽孢杆菌孢子的最外层，即外孢子囊，被称为间隙的空隙与被毛分开。外旋场和空间组合在很大程度上仍然是神秘的。因此，我们对驱动自然界中最普遍的细胞类型之一的组装的总体机制知之甚少。为了阐明外孢子囊组装的机制，我们产生了携带候选外孢子囊控制基因突变的菌株，并分析了对外孢子囊形成的影响。生化和细胞生物学分析认为，CotE指导CotO组装到孢子中，并且CotO可能位于或靠近帽的内侧。结合显示CotE和CotO在体外直接相互作用的数据，我们提出了一个模型，其中CotE和CotO是蛋白质相互作用网络的重要组成部分，该网络在帽形成和外孢子延伸期间连接外孢子和前孢子。我们的数据还表明，与模式生物枯草芽孢杆菌相比，帽干扰孢子一极的外壳组装，改变了外壳沉积的模式。我们认为，这两个物种之间被毛组合模式的差异是由于被毛组合固有的灵活性，这可能有助于孢子外层复杂性的进化。
This work dramatically improves our understanding of the assembly of the outermost layer of the B. anthracis spore, the exosporium, a layer that encases spores from many bacterial species and likely plays important roles in the spore’s interactions with the environment, including host tissues. Nonetheless, the mechanisms directing exosporium assembly into a shell surrounding the spore are still very poorly understood. In this study, we clarify these mechanisms by the identification of a novel protein interaction network that directs assembly to initiate at a specific subcellular location in the developing cell. Our results further suggest that the presence or absence of an exosporium has a major impact on the assembly of other more interior spore layers, thereby potentially explaining long-noted differences in spore assembly between B. anthracis and the model organism B. subtilis. Bacterial spores produced by the Bacillales are composed of concentric shells, each of which contributes to spore function. Spores from all species possess a cortex and coat, but spores from many species possess additional outer layers. The outermost layer of Bacillus anthracis spores, the exosporium, is separated from the coat by a gap known as the interspace. Exosporium and interspace assembly remains largely mysterious. As a result, we have a poor understanding of the overarching mechanisms driving the assembly of one of the most ubiquitous cell types in nature. To elucidate the mechanisms directing exosporium assembly, we generated strains bearing mutations in candidate exosporium-controlling genes and analyzed the effect on exosporium formation. Biochemical and cell biological analyses argue that CotE directs the assembly of CotO into the spore and that CotO might be located at or close to the interior side of the cap. Taken together with data showing that CotE and CotO interact directly in vitro, we propose a model in which CotE and CotO are important components of a protein interaction network that connects the exosporium to the forespore during cap formation and exosporium elongation. Our data also suggest that the cap interferes with coat assembly at one pole of the spore, altering the pattern of coat deposition compared to the model organism Bacillus subtilis. We propose that the difference in coat assembly patterns between these two species is due to an inherent flexibility in coat assembly, which may facilitate the evolution of spore outer layer complexity.