School of Molecular Cell Biology and Biotechnology, Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, 6997801, Israel.
Nat Microbiol. 2018 Jan;3(1):83-89. doi: 10.1038/s41564-017-0044-z. Epub 2017 Oct 16.
Bacterial cell-cell signalling, or quorum sensing, is characterized by the secretion and groupwide detection of small diffusible signal molecules called autoinducers. This mechanism allows cells to coordinate their behaviour in a density-dependent manner. A quorum-sensing cell may directly respond to the autoinducers it produces in a cell-autonomous and quorum-independent manner, but the strength of this self-sensing effect and its impact on bacterial physiology are unclear. Here, we explore the existence and impact of self-sensing in the Bacillus subtilis ComQXP and Rap-Phr quorum-sensing systems. By comparing the quorum-sensing response of autoinducer-secreting and non-secreting cells in co-culture, we find that secreting cells consistently show a stronger response than non-secreting cells. Combining genetic and quantitative analyses, we demonstrate this effect to be a direct result of self-sensing and rule out an indirect regulatory effect of the autoinducer production genes on response sensitivity. In addition, self-sensing in the ComQXP system affects persistence to antibiotic treatment. Together, these findings indicate the existence of self-sensing in the two most common designs of quorum-sensing systems of Gram-positive bacteria.
细菌细胞间信号传递，或群体感应，其特征是分泌和全群检测小的可扩散信号分子，称为自诱导物。这种机制允许细胞以密度依赖的方式协调其行为。群体感应细胞可能以细胞自主和群体独立的方式直接响应其产生的自诱导物，但这种自我感应效应的强度及其对细菌生理学的影响尚不清楚。在这里，我们探索了枯草芽孢杆菌 ComQXP 和 Rap-Phr 群体感应系统中自我感应的存在和影响。通过比较共培养中分泌和非分泌细胞的群体感应反应，我们发现分泌细胞的反应始终强于非分泌细胞。结合遗传和定量分析，我们证明这种效应是自我感应的直接结果，并排除了自诱导物产生基因对反应灵敏度的间接调节作用。此外，ComQXP 系统中的自我感应会影响对抗生素治疗的持久性。总之，这些发现表明，革兰氏阳性菌最常见的两种群体感应系统设计中存在自我感应。
