ssRNA phage penetration triggers detachment of the F-pilus
ssRNA phage penetration triggers detachment of the F-pilus
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DOI：
10.1073/pnas.2011901117
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发表时间：
2020-10-13
影响因子：
11.1
通讯作者：
Zeng, Lanying
中科院分区：
文献类型：
--
作者：
Harb, Laith;Chamakura, Karthik;Zeng, Lanying
虽然F特异性ssRNA噬菌体MS 2长期以来一直具有范例地位，但对基因组RNA（gRNA）渗透到细胞中知之甚少。噬菌体最初使用其成熟蛋白（Mat）与F菌毛结合，然后Mat结合的gRNA从病毒衣壳释放出来，并以某种方式穿过细菌包膜进入细胞质。为了解决这个过程的机制，我们荧光标记的ssRNA噬菌体MS 2跟踪感染过程中的F-菌毛动力学。我们发现ssRNA噬菌体感染触发宿主细胞释放F-菌毛，并且较高的感染复数（MOI）与较长F-菌毛的脱离相关。我们还报告说，进入宿主细胞质的gRNA需要F-质粒编码的偶联蛋白，TraD，它位于F-编码的IV型分泌系统（T4 SS）的细胞质入口。然而，TraD对于菌毛脱离不是必需的，表明脱离是由MS 2与F菌毛或T4 SS接合的早期步骤触发的。我们提出了一个多步模型，其中ssRNA噬菌体与F-菌毛结合，并通过菌毛收缩与细胞表面T4 SS通道的远端接合。持续的菌毛回缩将Mat-gRNA复合物从病毒体中拉出进入T4 SS通道，引起扭转应力，该扭转应力破坏细胞表面的成熟F-菌毛。我们建议，噬菌体诱导的F-菌毛动力学的中断提供了一个选择性的优势，感染ESTA，因此可能是普遍的ESTA之间的伸缩性皮利特定。
Although the F-specific ssRNA phage MS2 has long had paradigm status, little is known about penetration of the genomic RNA (gRNA) into the cell. The phage initially binds to the F-pilus using its maturation protein (Mat), and then theMat-bound gRNA is released from the viral capsid and somehow crosses the bacterial envelope into the cytoplasm. To address the mechanics of this process, we fluorescently labeled the ssRNA phage MS2 to track F-pilus dynamics during infection. We discovered that ssRNA phage infection triggers the release of F-pili from host cells, and that higher multiplicity of infection (MOI) correlates with detachment of longer F-pili. We also report that entry of gRNA into the host cytoplasm requires the F-plasmid-encoded coupling protein, TraD, which is located at the cytoplasmic entrance of the F-encoded type IV secretion system (T4SS). However, TraD is not essential for pilus detachment, indicating that detachment is triggered by an early step of MS2 engagement with the F-pilus or T4SS. We propose a multistep model in which the ssRNA phage binds to the F-pilus and through pilus retraction engages with the distal end of the T4SS channel at the cell surface. Continued pilus retraction pulls the Mat-gRNA complex out of the virion into the T4SS channel, causing a torsional stress that breaks the mature F-pilus at the cell surface. We propose that phage-induced disruptions of F-pilus dynamics provides a selective advantage for infecting phages and thus may be prevalent among the phages specific for retractile pili.