Phage Manipulation of Bacterial Quorum-Sensing-Mediated Communication

摘要/项目摘要 细菌因致病而臭名昭著，并因其有益而日益受到重视 在健康方面的作用。细菌可以作为自由游动的细胞存在，也可以作为表面附着群落的成员存在，称为 生物膜。生物膜对人体健康尤其有害。这些生活方式之间的转变是可以控制的 通过称为群体感知(QS)的细胞间通信过程。QS依赖于生产、发布、 积聚和检测称为自身诱导物(AIs)的细胞外信号分子。QS使细菌能够 协调集体行为，包括生物膜的形成和扩散。最近出现了一种噬菌体 发现劫持细菌QS AI并使用其中编码的信息来驱动裂解之间的转换 和溶原菌，首次报道了噬菌体-细菌QS介导的跨界通讯。噬菌体QS 名为VqmAphage的受体使噬菌体能够“调节”同源宿主QS AI，3，5- 二甲基吡嗪-2-醇(DPO)。这种窃听机制允许噬菌体执行其裂解周期 只在高宿主细胞密度下，推测最大限度地扩大了噬菌体的扩散。此外，这一机制使 噬菌体驱动宿主细菌生物被膜扩散的程序。我的目标是了解分子基础 以及这一新发现的噬菌体QS交叉通讯过程的生物学意义 模拟自然：非均匀的空间结构的噬菌体-细菌生物膜群落。我推测这个噬菌体 QS受体在感染后立即产生，提供传入噬菌体作为宿主的第一个迹象 细胞密度，使噬菌体能够在进入时适当地启动裂解或溶源程序。这就做 确定感染后这一途径何时被激活。其次，我假设自然的、宿主产生的 VqmA噬菌体表达诱导剂启动正反馈环，促进噬菌体快速转变 仅在高宿主细胞密度下进入裂解阶段。我将鉴定vqmAphage的内源诱导物 转录，并探索诱导子在噬菌体和寄主生物学中的作用。最后，我预测噬菌体介导的 裂解主要发生在生物膜的细胞密度最高的区域，促进宿主的扩散和增加 噬菌体扩散到新的宿主细胞。我将定义噬菌体QS介导的裂解的空间和时间动力学 Biofilms和我将监测对生物膜、噬菌体传播和宿主细胞扩散的影响。 总的来说，我的工作将定义通过QS发生的噬菌体-细菌王国之间的相互作用。我的发现 也有助于开发控制细菌感染的新方法，无论是通过噬菌体 治疗方法、生物膜破坏策略或这两种方法的组合。为了实现这一目标 项目，我将成为分子生物学，细菌遗传学，成像技术，科学写作， 研讨会演讲、教学和辅导。作为一名博士后研究员，我所掌握的发现技能 对我建立自己的独立学术实验室是至关重要的，专注于研究 噬菌体-细菌群落。

ABSTRACT / PROJECT SUMMARY Bacteria are notorious for causing disease and increasingly becoming appreciated for their beneficial roles in health. Bacteria can exist as free-swimming cells or as members of surface-attached communities called biofilms. Biofilms are particularly detrimental to human health. Transitions between these lifestyles are controlled by the cell-cell communication process called quorum sensing (QS). QS relies on the production, release, accumulation, and detection of extracellular signal molecules called autoinducers (AIs). QS enables bacteria to orchestrate collective behaviors including biofilm formation and dispersal. A bacteriophage was recently discovered that hijacks a bacterial QS AI and uses the information encoded in it to drive transitions between lysis and lysogeny, the first report of phage-bacterial QS-mediated inter-kingdom-communication. The phage QS receptor called VqmAPhage enables the phage to “tune into” the accumulation of the cognate host QS AI, 3,5- dimethylpyrazin-2-ol (DPO). This eavesdropping mechanism allows the phage to execute its lytic cycle exclusively at high host cell density, presumably maximizing phage spread. Moreover, this mechanism enables the phage to drive the host bacterial biofilm dispersal program. My aims are to understand the molecular basis and biological significance of this newly-discovered phage QS cross-communication process in contexts that mimic nature: non-uniform spatially structured phage-bacterial biofilm communities. I hypothesize that the phage QS receptor is produced immediately following infection providing incoming phages the first indication of host cell density, enabling the phage to appropriately launch either the lysis or the lysogeny program upon entry. I will define when this pathway is activated following infection. Second, I hypothesize that the natural, host-produced inducer of vqmAPhage expression primes a positive feedback loop that promotes the rapid transition of the phage to the lytic phase exclusively at high host cell density. I will identify the endogenous inducer of vqmAPhage transcription and explore the role of the inducer in phage and host biology. Finally, I predict that phage-mediated lysis occurs primarily at the highest cell density regions of biofilms, promoting both host dispersal and increased phage spread to new host cells. I will define the spatial and temporal dynamics of phage QS-mediated lysis in biofilms and I will monitor the consequences to the biofilm, to phage transmission, and to host cell dispersal. Collectively, my work will define phage-bacterial inter-kingdom interactions that occur through QS. My findings could also contribute to the development of new approaches to control bacterial infections, either through phage therapies, biofilm disruption strategies, or a combination of the two approaches. To accomplish the goals of this project, I will become expert in molecular biology, bacterial genetics, imaging technologies, scientific writing, seminar speaking, teaching, and mentoring. The skills I master as I make discoveries as a postdoctoral fellow will be crucial to prepare me to establish my own independent academic laboratory focused on investigations of phage-bacterial communities.