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Issue 4, 2011
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Lyngbyoic acid, a “tagged” fatty acid from a marine cyanobacterium, disrupts quorum sensing in Pseudomonas aeruginosa

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Abstract

Quorum sensing (QS) is a mechanism of bacterial gene regulation in response to increases in population density. Perhaps most studied are QS pathways mediated by acylhomoserine lactones (AHLs) in Gram-negative bacteria. Production of small molecule QS signals, their accumulation within a diffusion-limited environment and their binding to a LuxR-type receptor trigger QS-controlled gene regulatory cascades. In Pseudomonas aeruginosa, for example, binding of AHLs to their cognate receptors (LasR, RhlR) controls production of virulence factors, pigments, antibiotics and other behaviors important for its interactions with eukaryotic hosts and other bacteria. We have previously shown that marine cyanobacteria produce QS-inhibitory molecules, including 8-epi-malyngamide C (1), malyngamide C (2) and malyngolide (3). Here we isolated a new small cyclopropane-containing fatty acid, lyngbyoic acid (4), as a major metabolite of the marine cyanobacterium, Lyngbya cf. majuscula, collected at various sites in Florida. We screened 4 against four reporters based on different AHL receptors (LuxR, AhyR, TraR and LasR) and found that 4 most strongly affected LasR. We also show that 4 reduces pyocyanin and elastase (LasB) both on the protein and transcript level in wild-type P. aeruginosa, and that 4 directly inhibits LasB enzymatic activity. Conversely, dodecanoic acid (9) increased pyocyanin and LasB, demonstrating that the fused cyclopropane “tag” is functionally relevant and potentially confers resistance to β-oxidation. Global transcriptional effects of 4 in some ways replicate the gene expression changes of P. aeruginosa during chronic lung infections of cystic fibrosis patients, with reduced lasR signaling, increased biofilm and expression of the virulence locus HSI-I. Compound 4 may therefore prove to be a useful tool in the study of P. aeruginosa adaption during such chronic infections.

Graphical abstract: Lyngbyoic acid, a “tagged” fatty acid from a marine cyanobacterium, disrupts quorum sensing in Pseudomonas aeruginosa

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Supplementary files

Article information


Submitted
27 Aug 2010
Accepted
09 Dec 2010
First published
24 Jan 2011

Mol. BioSyst., 2011,7, 1205-1216
Article type
Paper

Lyngbyoic acid, a “tagged” fatty acid from a marine cyanobacterium, disrupts quorum sensing in Pseudomonas aeruginosa

J. C. Kwan, T. Meickle, D. Ladwa, M. Teplitski, V. Paul and H. Luesch, Mol. BioSyst., 2011, 7, 1205
DOI: 10.1039/C0MB00180E

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