Novel anti-phage resistance mechanisms channelled through transcriptional regulation

通过转录调控引导的新型抗噬菌体抗性机制

• 批准号: 464976318
• 负责人: Professorin Dr. Debbie Lindell, Ph.D.
• 金额: --
• 依托单位: Institut für Biologie III
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/464976318?language=en
• 关键词: Novel; anti; phage; resistance; mechanisms

Marine unicellular cyanobacteria of the genera Synechococcus and Prochlorococcus are important primary producers in the world’s oceans. Their coexistence with high abundances of cyanophages is likely due to effective mechanisms of resistance. Previously, we have shown that generalist (broad host-range) T4-like cyanophages have identical transcriptional programs in multiple sensitive host strains. Since this family of phages does not code for its own RNA polymerase it must usurp that of its hosts. The means through which this program is regulated at the molecule level is significantly different to the T4 archetype phage and remains unknown. In addition, we have shown that generalist cyanophages attach and enter into resistant cyanobacterial cells, yet do not complete the infection cycle. A common feature of halted infections in resistant cyanobacteria is significantly reduced transcription of phage genes. The vast majority of these marine cyanobacteria lack known resistance mechanisms such as CRISPR-Cas or restriction-modification systems. This indicates that presently unknown intracellular defense mechanisms are at play. In this priority program our objectives are to address the central question of how the phage transcriptional program of marine T4-like cyanophages is regulated in sensitive cyanobacteria and to elucidate the mechanisms of defence that function at the transcriptional level in resistant cyanobacteria. Our specific objectives are to: (1) Identify host and phage factors that regulate phage promoters; (2) Elucidate phage factors that interact with the host RNA polymerase; (3) Investigate the role of key host and phage proteins in phage transcription; and (4) Discover cyanobacterial resistance mechanisms that reduce transcription. We will use the T4-like cyanophage, Syn9, with the sensitive Synechococcus WH8109 and resistant Synechococcus CC9311 as our model system, all of which can be genetically manipulated. To achieve these aims we will identify phage and host proteins that are directly involved in regulation of phage promoter activity and modulate transcription. We will determine whether this is through direct interaction with phage promoters or through the chemical modification of, or protein-protein interactions with, the host RNA polymerase. We will generate mutants lacking these factors to assess the impact on the infection process. Furthermore, we will ascertain what inhibits the phage transcriptional program in the resistant cyanobacterium. This study will provide fundamental information on the novel means through which the marine T4-like cyanophages regulate their transcriptional program relative to that in the T4 archetype. Furthermore, this will lay the groundwork for the discovery of new anti-viral defence systems that function at the transcriptional level. As such this research program will open up new horizons in the understanding of host-virus interactions in this ecologically important group of organisms.

聚藻属和原绿球藻属的海洋单细胞蓝藻是世界海洋中重要的初级生产者。它们与高丰度的噬藻体共存可能是由于有效的耐药机制。以前，我们已经证明了通才（广泛的宿主范围）t4样蓝噬体在多个敏感宿主菌株中具有相同的转录程序。由于这个噬菌体家族不为自己的RNA聚合酶编码，它必须篡夺宿主的RNA聚合酶。该程序在分子水平上的调节方式与T4原型噬菌体有显著不同，目前尚不清楚。此外，我们已经表明，多面手的噬藻体附着并进入耐药的蓝藻细胞，但不完成感染周期。在耐药蓝藻中停止感染的一个共同特征是噬菌体基因的转录显著减少。这些海洋蓝藻绝大多数缺乏已知的抗性机制，如CRISPR-Cas或限制性修饰系统。这表明目前未知的细胞内防御机制在起作用。在这个优先项目中，我们的目标是解决海洋t4样蓝藻噬菌体转录程序如何在敏感蓝藻中调节的核心问题，并阐明在抗性蓝藻中转录水平起作用的防御机制。我们的具体目标是：(1)确定调节噬菌体启动子的宿主和噬菌体因子；(2)阐明与宿主RNA聚合酶相互作用的噬菌体因子；(3)研究关键宿主蛋白和噬菌体蛋白在噬菌体转录中的作用；(4)发现减少转录的蓝藻耐药机制。我们将使用t4样的噬藻体Syn9，与敏感的聚球菌WH8109和耐药的聚球菌CC9311作为我们的模型系统，所有这些都可以进行基因操作。为了实现这些目标，我们将鉴定直接参与噬菌体启动子活性调节和转录调节的噬菌体和宿主蛋白。我们将确定这是通过与噬菌体启动子的直接相互作用，还是通过对宿主RNA聚合酶的化学修饰或蛋白质与蛋白质的相互作用。我们将产生缺乏这些因素的突变体来评估对感染过程的影响。此外，我们将确定是什么抑制了耐药蓝藻中的噬菌体转录程序。本研究将为海洋T4样噬藻调节其转录程序的新途径提供基础信息。此外，这将为发现在转录水平上起作用的新抗病毒防御系统奠定基础。因此，这项研究计划将为了解宿主-病毒在这一生态重要生物群体中的相互作用开辟新的视野。