Identification of genes controlled by quorum sensing in <i>Pseudomonas aeruginosa</i>

TLDR

Quorum sensing enables bacteria to coordinate gene expression in a cell‑density‑dependent manner. This study aimed to systematically identify the genes regulated by quorum sensing in *Pseudomonas aeruginosa*. A promoterless lacZ transposon library was constructed in an acyl‑HSL synthesis mutant and screened for HSL‑induced β‑galactosidase activity. Thirty‑nine genes were found to be quorum‑sensing regulated, clustered into distinct classes, many forming operons or genomic patches, and most encode putative virulence factors or secondary metabolites with strong HSL induction.

Abstract

Bacteria communicate with each other to coordinate expression of specific genes in a cell density-dependent fashion, a phenomenon called quorum sensing and response. Although we know that quorum sensing via acyl-homoserine lactone (HSL) signals controls expression of several virulence genes in the human pathogen Pseudomonas aeruginosa , the number and types of genes controlled by quorum sensing have not been studied systematically. We have constructed a library of random insertions in the chromosome of a P. aeruginosa acyl-HSL synthesis mutant by using a transposon containing a promoterless lacZ . This library was screened for acyl-HSL induction of lacZ . Thirty-nine quorum sensing-regulated genes were identified. The genes were organized into classes depending on the pattern of regulation. About half of the genes appear to be in seven operons, some seem organized in large patches on the genome. Many of the quorum sensing-regulated genes code for putative virulence factors or production of secondary metabolites. Many of the genes identified showed a high level of induction by acyl-HSL signaling.