Bacterial quorum-sensing signals are inactivated by mammalian cells
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138
Quorum sensing is a cell-to-cell communication system used by pathogenic bacteria to control expression of virulence factors (1–6). In Pseudomonas aeruginosa, quorum-sensing mutants show reduced virulence (1–3, 7, 8), and, in a recent issue of PNAS, Chun et al. (9) reported that human respiratory epithelia have the capacity to inactivate a P. aeruginosa quorum-sensing signal. This capacity appears to be enzymatic in nature, and it functions in some but not all mammalian cells. This finding opens a new area of research and indicates that humans have evolved mechanisms to interfere with a quorum-sensing pathway.
Quorum-Sensing Signal Molecules
P. aeruginosa produces two quorum-sensing signal molecules, N-(3-oxodode-canoyl)-l-homoserine lactone (3OC12-HSL) and N-butanoyl-l-homoserine lactone (C4-HSL), that regulate production of virulence factors and biofilm formation. These compounds are produced extracellularly and, at sufficient concentrations, can induce transcription of a battery of virulence genes. In well studied strains, quorum sensing is hierarchical: threshold levels of 3OC12-HSL are required to activate C4-HSL production (10 …
