Florez Catalina, Raab Julie E, Cooke Adam C, Schertzer Jeffrey W
Department of Biological Sciences, Binghamton University, Binghamton, New York, USA, and Binghamton Biofilm Research Center, Binghamton University, Binghamton, New York, USA.
Department of Biological Sciences, Binghamton University, Binghamton, New York, USA, and Binghamton Biofilm Research Center, Binghamton University, Binghamton, New York, USA
mBio. 2017 Aug 8;8(4):e01034-17. doi: 10.1128/mBio.01034-17.
The quinolone signal (PQS) is an important quorum-sensing molecule in that also mediates its own packaging and transport by stimulating outer membrane vesicle (OMV) formation. Because OMVs have been implicated in many virulence-associated behaviors, it is critical that we understand how they are formed. Our group proposed the bilayer-couple model for OMV biogenesis, where PQS intercalates into the outer membrane, causing expansion of the outer leaflet and consequently inducing curvature. In accordance with the model, we hypothesized that PQS must be transported from the cytoplasm to the outer membrane before it can initiate OMV formation. We initially examined two laboratory strains of and found significant strain-dependent differences. PQS export correlated strongly with OMV production, even though equivalent amounts of total PQS were produced by both strains. Interestingly, we discovered that poor OMV producers sequestered the majority of PQS in the inner membrane, which appeared to be the result of early saturation of the export pathway. Further analysis showed that strain-specific PQS export and OMV biogenesis patterns were stable once established but could be significantly altered by changing the growth medium. Finally, we demonstrated that the associations described for laboratory strains also held for three clinical strains. These results suggest that factors controlling the export of PQS dictate OMV biogenesis. This work provides new insight into PQS-controlled virulence in and provides important tools to further study signal export and OMV biogenesis. Bacterial secretion has been recognized as an essential facet of microbial pathogenesis and human disease. Numerous virulence factors have been found to be transported within outer membrane vesicles (OMVs), and delivery using these biological nanoparticles often results in increased potency. OMV biogenesis is an important but poorly understood process that is ubiquitous among Gram-negative organisms. Our group seeks to understand the biochemical mechanisms behind the formation of OMVs and has developed a model of small-molecule-induced membrane curvature as an important driver of this process. With this work, we demonstrate that PQS, a known small-molecule OMV inducer, must be exported to promote OMV biogenesis in both lab-adapted and clinical strains of In supporting and expanding the bilayer-couple model of OMV biogenesis, the current work lays the groundwork for studying environmental and genetic factors that modulate OMV production and, consequently, the packaging and delivery of many bacterial factors.
喹诺酮信号（PQS）是一种重要的群体感应分子，它还通过刺激外膜囊泡（OMV）的形成来介导自身的包装和运输。由于OMV与许多毒力相关行为有关，因此了解它们的形成方式至关重要。我们小组提出了OMV生物发生的双层偶联模型，其中PQS插入外膜，导致外小叶扩张，从而诱导曲率。根据该模型，我们假设PQS必须从细胞质转运到外膜，才能启动OMV的形成。我们最初检查了两种实验室菌株，发现了显著的菌株依赖性差异。PQS的输出与OMV的产生密切相关，尽管两种菌株产生的总PQS量相等。有趣的是，我们发现OMV产生能力差的菌株将大部分PQS隔离在内膜中，这似乎是输出途径早期饱和的结果。进一步分析表明，菌株特异性的PQS输出和OMV生物发生模式一旦建立就很稳定，但可以通过改变生长培养基而显著改变。最后我们证明，实验室菌株中描述的关联在三种临床菌株中也成立。这些结果表明，控制PQS输出的因素决定了OMV的生物发生。这项工作为PQS控制的毒力提供了新的见解，并为进一步研究信号输出和OMV生物发生提供了重要工具。细菌分泌已被认为是微生物发病机制和人类疾病的一个重要方面。已发现许多毒力因子在外膜囊泡（OMV）内运输，使用这些生物纳米颗粒进行递送通常会提高效力。OMV生物发生是一个重要但了解甚少的过程，在革兰氏阴性菌中普遍存在。我们小组试图了解OMV形成背后的生化机制，并开发了一种小分子诱导膜曲率的模型，作为这一过程的重要驱动因素。通过这项工作，我们证明，已知的小分子OMV诱导剂PQS必须输出，才能促进实验室适应菌株和临床菌株中的OMV生物发生。在支持和扩展OMV生物发生的双层偶联模型方面，目前的工作为研究调节OMV产生的环境和遗传因素奠定了基础，从而也为研究许多细菌因子的包装和递送奠定了基础。
