title: Identification of five structurally unrelated quorum-sensing inhibitors of Pseudomonas aeruginosa from a natural-derivative database.
abstract: Bacteria communicate by means of small signal molecules in a process termed quorum sensing (QS). QS enables bacteria to organize their activities at the population level, including the coordinated secretion of virulence factors. Certain small-molecule compounds, known as quorum-sensing inhibitors (QSIs), have been shown to effectively block QS and subsequently attenuate the virulence of Pseudomonas aeruginosa, as well as increasing its susceptibility to both antibiotics and the immune system. In this study, a structure-based virtual screening (SB-VS) approach was used for the discovery of novel QSI candidates. Three-dimensional structures of 3,040 natural compounds and their derivatives were obtained, after which molecular docking was performed using the QS receptor LasR as a target. Based on docking scores and molecular masses, 22 compounds were purchased to determine their efficacies as quorum-sensing inhibitors. Using a live reporter assay for quorum sensing, 5 compounds were found to be able to inhibit QS-regulated gene expression in P. aeruginosa in a dose-dependent manner. The most promising compound, G1, was evaluated by isobaric tag for relative and absolute quantitation (iTRAQ)-based proteomic analysis, and it was found to significantly affect the abundance of 46 proteins (19 were upregulated; 27 were downregulated) in P. aeruginosa PAO1. It specifically reduced the expression of several quorum-sensing-regulated virulence factors, such as protease IV, chitinase, and pyoverdine synthetases. G1 was also able to reduce extracellular DNA release and inhibited the secretion of the virulence factor, elastase, whose expression is regulated by LasR. These results demonstrate the utility of SB-VS for the discovery of target-specific QSIs.
authors.affiliation: Singapore Centre on Environmental Life Sciences Engineering (SCELSE), Nanyang Technological University, Singapore.
authors.forename: Sean Yang-Yi
authors.initials: SY
authors.lastname: Tan
authors.forename: Song-Lin
authors.initials: SL
authors.lastname: Chua
authors.forename: Yicai
authors.initials: Y
authors.lastname: Chen
authors.forename: Scott A
authors.initials: SA
authors.lastname: Rice
authors.forename: Staffan
authors.initials: S
authors.lastname: Kjelleberg
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Nielsen
authors.forename: Liang
authors.initials: L
authors.lastname: Yang
authors.forename: Michael
authors.initials: M
authors.lastname: Givskov
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002688:Chitinases / Q000235:genetics / Q000378:metabolism; D018360:Crystallography, X-Ray; D062126:Databases, Chemical; D055808:Drug Discovery; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D062105:Molecular Docking Simulation; D010196:Pancreatic Elastase / Q000235:genetics / Q000378:metabolism; D010447:Peptide Hydrolases / Q000235:genetics / Q000378:metabolism; D010453:Peptide Synthases / Q000235:genetics / Q000378:metabolism; D040901:Proteomics; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D053038:Quorum Sensing / Q000187:drug effects*; D054852:Small Molecule Libraries / Q000737:chemistry / Q000494:pharmacology*; D015534:Trans-Activators / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; C080365:LasR protein, Pseudomonas aeruginosa; D054852:Small Molecule Libraries; D015534:Trans-Activators; D037521:Virulence Factors; D002688:Chitinases; D010447:Peptide Hydrolases; D010196:Pancreatic Elastase; C030732:protease IV; D010453:Peptide Synthases; C091136:pyoverdine synthetase protein, Pseudomonas