Forschungszentrum Jülich GmbH, Institute for Bio- and Geosciences 1, IBG1, 52425 Jülich, Germany.
Forschungszentrum Jülich GmbH, Institute for Bio- and Geosciences 1, IBG1, 52425 Jülich, Germany.
J Mol Biol. 2019 Nov 22;431(23):4670-4683. doi: 10.1016/j.jmb.2019.02.011. Epub 2019 Feb 21.
Phages, viruses that prey on bacteria, are the most abundant and diverse inhabitants of the Earth. Temperate bacteriophages can integrate into the host genome and, as so-called prophages, maintain a long-term association with their host. The close relationship between host and virus has significantly shaped microbial evolution and phage elements may benefit their host by providing new functions. Nevertheless, the strong activity of phage promoters and potentially toxic gene products may impose a severe fitness burden and must be tightly controlled. In this context, xenogeneic silencing (XS) proteins, which can recognize foreign DNA elements, play an important role in the acquisition of novel genetic information and facilitate the evolution of regulatory networks. Currently known XS proteins fall into four classes (H-NS, MvaT, Rok and Lsr2) and have been shown to follow a similar mode of action by binding to AT-rich DNA and forming an oligomeric nucleoprotein complex that silences gene expression. In this review, we focus on the role of XS proteins in phage-host interactions by highlighting the important function of XS proteins in maintaining the lysogenic state and by providing examples of how phages fight back by encoding inhibitory proteins that disrupt XS functions in the host. Sequence analysis of available phage genomes revealed the presence of genes encoding Lsr2-type proteins in the genomes of phages infecting Actinobacteria. These data provide an interesting perspective for future studies to elucidate the impact of phage-encoded XS homologs on the phage life cycle and phage-host interactions.
噬菌体是一种以细菌为食的病毒，是地球上数量最多、多样性最丰富的生物。温和噬菌体可以整合到宿主基因组中，并作为所谓的前噬菌体，与宿主保持长期的联系。宿主和病毒之间的密切关系极大地影响了微生物的进化，噬菌体元素可能通过提供新的功能而使宿主受益。然而，噬菌体启动子的强烈活性和潜在的毒性基因产物可能会带来严重的适应负担，必须进行严格的控制。在这种情况下，能够识别外源 DNA 元件的异源沉默（XS）蛋白在获取新的遗传信息和促进调控网络的进化方面发挥着重要作用。目前已知的 XS 蛋白分为四类（H-NS、MvaT、Rok 和 Lsr2），通过与富含 AT 的 DNA 结合并形成寡聚核蛋白复合物来沉默基因表达，它们的作用机制相似。在这篇综述中，我们通过强调 XS 蛋白在维持溶原状态方面的重要功能，以及通过提供噬菌体编码抑制蛋白来干扰宿主中的 XS 功能的例子，来关注 XS 蛋白在噬菌体-宿主相互作用中的作用。对现有噬菌体基因组的序列分析表明，在感染放线菌的噬菌体基因组中存在编码 Lsr2 型蛋白的基因。这些数据为未来的研究提供了一个有趣的视角，以阐明噬菌体编码的 XS 同源物对噬菌体生命周期和噬菌体-宿主相互作用的影响。
