Abstract
In a process termed quorum sensing, bacteria use diffusible chemical signals to coordinate cell density-dependent gene expression. In the human pathogen
Pseudomonas aeruginosa
, quorum sensing controls hundreds of genes, many of which encode extracellular virulence factors. Quorum sensing is required for
P. aeruginosa
virulence in animal models. Curiously, quorum sensing-deficient variants, most of which carry a mutation in the gene encoding the central quorum sensing regulator
lasR
, are frequently isolated from acute and chronic infections. The mechanism for their emergence is not known. Here we provide experimental evidence suggesting that these
lasR
mutants are social cheaters that cease production of quorum-controlled factors and take advantage of their production by the group. We detected an emerging subpopulation of
lasR
mutants after ≈100 generations of
in vitro
evolution of the
P. aeruginosa
wild-type strain under culture conditions that require quorum sensing for growth. Under such conditions, quorum sensing appears to impose a metabolic burden on the proliferating bacterial cell, because quorum-controlled genes not normally induced until cessation of growth were highly expressed early in growth, and a defined
lasR
mutant showed a growth advantage when cocultured with the parent strain. The emergence of quorum-sensing-deficient variants in certain environments is therefore an indicator of high quorum sensing activity of the bacterial population as a whole. It does not necessarily indicate that quorum sensing is insignificant, as has previously been suggested. Thus, novel antivirulence strategies aimed at disrupting bacterial communication may be particularly effective in such clinical settings.
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Metrics
461
Citations
50
References
Details
Published
Oct 02, 2007
Vol/Issue
104(40)
Pages
15876-15881
Cite This Article
Kelsi M. Sandoz, Shelby M. Mitzimberg, Martin Schuster (2007). Social cheating in Pseudomonas aeruginosa quorum sensing. Proceedings of the National Academy of Sciences, 104(40), 15876-15881. https://doi.org/10.1073/pnas.0705653104