earticle

영어

Quorum sensing (QS) is a cell density-dependent signaling system used by bacteria to coordinate gene expression within their population. In the QS mechanism of many gram-negative bacteria, acyl homoserine lactones (AHLs) are known to be the triggering molecules which form a complex with a transcriptional activator protein and promote the binding of the complex to DNA regulatory site activating transcription of many virulence genes. In this study, we describe the development and characterization of in vivo cell-based bioassay systems for detecting QS inhibitors based on three members of the LuxR family proteins, TraR, LasR and the recently identified QscR. Three different gram-negative bacteria, Escherichia coli, Agrobacterium tumefaciens and Pseudomonas aeruginosa, were used as reporter strains to over-produce one of the QS activator proteins and respond to AHLs and/or their inhibitors. The nine different in vivo assay systems (3 reporter strains × 3 QS proteins) were evaluated for their applicability and reliability by studying quantitative responses to various AHLs and furanones, the latter of which were observed as potent inhibitors against AHLs. The results indicate that, although they do not detect direct binding between QS proteins and AHLs and/or inhibiting molecules, the cell-based in vivo bioassay systems are a sensitive and reliable tool for screening of QS activators and inhibitors. This study also suggests that furanones are potentially important QS inhibitors for many LuxR-type activator proteins.