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首页> 外文期刊>Journal of bacteriology >Decoupling Filamentous Phage Uptake and Energy of the TolQRA Motor in Escherichia coli
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Decoupling Filamentous Phage Uptake and Energy of the TolQRA Motor in Escherichia coli

机译：在大肠杆菌中去耦丝状噬菌体摄取和托电运动马达的能量

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Filamentous phages are nonlytic viruses that specifically infect bacteria, establishing a persistent association with their host. The phage particle has no machinery for generating energy and parasitizes its host’s existing structures in order to cross the bacterial envelope and deliver its genetic material. The import of filamentous phages across the bacterial periplasmic space requires some of the components of a macrocomplex of the envelope known as the Tol system. This complex uses the energy provided by the proton motive force (pmf) of the inner membrane to perform essential and highly energy-consuming functions of the cell, such as envelope integrity maintenance and cell division. It has been suggested that phages take advantage of pmf-driven conformational changes in the Tol system to transit across the periplasm. However, this hypothesis has not been formally tested. In order to decouple the role of the Tol system in cell physiology and during phage parasitism, we used mutations on conserved essential residues known for inactivating pmf-dependent functions of the Tol system. We identified impaired Tol complexes that remain fully efficient for filamentous phage uptake. We further demonstrate that the TolQ-TolR homologous motor ExbB-ExbD, normally operating with the TonB protein, is able to promote phage infection along with full-length TolA. IMPORTANCE Filamentous phages are widely distributed symbionts of Gram-negative bacteria, with some of them being linked to genome evolution and virulence of their host. However, the precise mechanism that permits their uptake across the cell envelope is poorly understood. The canonical phage model Fd requires the TolQRA protein complex in the host envelope, which is suspected to translocate protons across the inner membrane. In this study, we show that phage uptake proceeds in the presence of the assembled but nonfunctional TolQRA complex. Moreover, our results unravel an alternative route for phage import that relies on the ExbB-ExbD proteins. This work provides new insights into the fundamental mechanisms of phage infection and might be generalized to other filamentous phages responsible for pathogen emergence.
机译：丝状噬菌体是特异性感染细菌的非腺性病毒，与其宿主建立持续关联。噬菌体颗粒没有用于产生能量的机械，并寄出其宿主的现有结构，以交叉细菌包膜并递送其遗传物质。在细菌周质空间上导入丝状噬菌体需要称为TOL系统的包膜的一些组分。该复合物利用内膜的质子动力（PMF）提供的能量来表现细胞的必要和高耗能的功能，例如包络完整性维持和细胞分裂。有人建议，噬菌体利用了TOL系统的PMF驱动的构象变化来过度推移周倍。然而，这个假设尚未正式测试。为了将Tol系统在细胞生理学和噬菌体寄生期间分离的作用，我们使用了所知的保守基本残留物的突变，用于灭活Tol系统的PMF依赖性功能。我们确定了对丝状噬菌体摄取仍然有效的脂肪复合物。我们进一步证明，通常与TONB蛋白操作的TOLQ-TOTR同源马达EDBB-EXBD能够促进噬菌体感染以及全长托拉。重要性丝状噬菌体是革兰氏阴性细菌的广泛分布式分布式，其中一些与其宿主的基因组演化和毒力有关。然而，允许它们在细胞包络上摄取的精确机制很差。规范噬菌体模型FD需要在宿主包络中的托状蛋白质复合物，其怀疑在内膜上翻转质子。在这项研究中，我们表明噬菌体摄取在组装但无功能的托QRA复合物的存在下进行。此外，我们的结果解开了依赖于exbb-exbd蛋白的噬菌体导入的替代途径。这项工作为噬菌体感染的基本机制提供了新的洞察力，并且可以推广到负责病原体出现的其他丝状噬菌体。

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