Quorum sensing modulates colony morphology through alkyl quinolones in Pseudomonas aeruginosa

BMC Microbiology

Martin Schuster¹  Rashmi Gupta¹ 

[1] Department of Microbiology, Oregon State University, Corvallis, OR 97331, USA

关键词: Biofilm;    Exopolysaccharide;    Acyl-homoserine lactone;    Alkylquinolone;    Colony;    Pseudomonas aeruginosa;    Quorum sensing;   

Others  :  1222019
DOI  :  10.1186/1471-2180-12-30

 received in 2011-07-07, accepted in 2012-03-09,  发布年份 2012

【 摘 要 】

Background

Acyl-homoserine lactone (acyl-HSL) and alkyl quinolone (AQ) based quorum-sensing (QS) systems are important for Pseudomonas aeruginosa virulence and biofilm formation. The effect of QS on biofilm formation is influenced by various genetic and environmental factors. Here, we used a colony biofilm assay to study the effect of the central acyl-HSL QS regulator, LasR, on biofilm formation and structure in the representative clinical P. aeruginosa isolate ZK2870.

Results

A lasR mutant exhibited wrinkled colony morphology at 37°C in contrast to the smooth colony morphology of the wild-type. Mutational analysis indicated that wrinkling of the lasR mutant is dependent on pel, encoding a biofilm matrix exopolysaccharide. Suppressor mutagenesis and complementation analysis implicated the AQ signaling pathway as the link between las QS and colony morphology. In this pathway, genes pqsA-D are involved in the synthesis of 4-hydroxyalkyl quinolines ("Series A congeners"), which are converted to 3,4-dihydroxyalkyl quinolines ("Series B congeners", including the well-characterized Pseudomonas Quinolone Signal, PQS) by the product of the LasR-dependent pqsH gene. Measurement of AQ in the wild-type, the lasR pqsA::Tn suppressor mutant as well as the defined lasR, pqsH, and lasR pqsH mutants showed a correlation between 4-hydroxyalkyl quinoline levels and the degree of colony wrinkling. Most importantly, the lasR pqsH double mutant displayed wrinkly morphology without producing any 3,4-dihydroxyalkyl quinolines. Constitutive expression of pqsA-D genes in a lasR pqsR::Tnmutant showed that colony wrinkling does not require the AQ receptor PqsR.

Conclusions

Taken together, these results indicate that the las QS system represses Pel and modulates colony morphology through a 4-hydroxyalkyl quinoline in a PqsR-independent manner, ascribing a novel function to an AQ other than PQS in P. aeruginosa.

【 授权许可】

   
2012 Gupta and Schuster; licensee BioMed Central Ltd.

【 图 表 】

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