Quorum Sensing in Pseudomonas aeruginosa

Quorum sensing is often depicted as a hierarchical and somewhat linear signaling pathway. However, recent work indicates that the pathways involved are highly interconnected with other signaling systems in the cell, as well as with core metabolic functions. Therefore, quorum sensing can best be viewed as a component of a wider network of signaling pathways, which collectively cooperate to fine-tune the cell’s adaptive response to environmental challenges. Here, we review the robustness of this arrangement and examine how it can contribute toward phenotypic diversification in otherwise clonal populations of cells. We also examine how, over the last decade, large-scale data collection (’omics) is gradually revealing regulatory architectures that could not be derived through more simple modes of analysis. Perhaps the biggest surprise of recent times has been the revelation that in pathogenic species, quorum sensing not only regulates virulence factor production but it also plays a major role in re-wiring cellular metabolism. We assess the consequences of this and delve deeper into whether the quorum sensing metabolism axis arises due to “cause or effect.”