title: Plant phenolic volatiles inhibit quorum sensing in pectobacteria and reduce their virulence by potential binding to ExpI and ExpR proteins.
abstract: Quorum sensing (QS) is a population density-dependent regulatory system in bacteria that couples gene expression to cell density through accumulation of diffusible signaling molecules. Pectobacteria are causal agents of soft rot disease in a range of economically important crops. They rely on QS to coordinate their main virulence factor, production of plant cell wall degrading enzymes (PCWDEs). Plants have evolved an array of antimicrobial compounds to anticipate and cope with pathogens, of which essential oils (EOs) are widely recognized. Here, volatile EOs, carvacrol and eugenol, were shown to specifically interfere with QS, the master regulator of virulence in pectobacteria, resulting in strong inhibition of QS genes, biofilm formation and PCWDEs, thereby leading to impaired infection. Accumulation of the signal molecule N-acylhomoserine lactone declined upon treatment with EOs, suggesting direct interaction of EOs with either homoserine lactone synthase (ExpI) or with the regulatory protein (ExpR). Homology models of both proteins were constructed and docking simulations were performed to test the above hypotheses. The resulting binding modes and docking scores of carvacrol and eugenol support potential binding to ExpI/ExpR, with stronger interactions than previously known inhibitors of both proteins. The results demonstrate the potential involvement of phytochemicals in the control of Pectobacterium.
authors.affiliation: Department of Plant Pathology and Microbiology and the Otto Warburg Minerva Center for Agricultural Biotechnology, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel.|Department of Plant Sciences, Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel.
authors.forename: Janak Raj
authors.initials: JR
authors.lastname: Joshi
authors.affiliation: Department of Chemistry, Bar-Ilan University, Ramat-Gan, Israel.
authors.forename: Netaly
authors.initials: N
authors.lastname: Khazanov
authors.affiliation: Department of Chemistry, Bar-Ilan University, Ramat-Gan, Israel.
authors.forename: Hanoch
authors.initials: H
authors.lastname: Senderowitz
authors.affiliation: Department of Plant Pathology and Microbiology and the Otto Warburg Minerva Center for Agricultural Biotechnology, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel.
authors.forename: Saul
authors.initials: S
authors.lastname: Burdman
authors.affiliation: Department of Plant Sciences, Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel.
authors.forename: Alexander
authors.initials: A
authors.lastname: Lipsky
authors.affiliation: Department of Plant Sciences, Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel.
authors.forename: Iris
authors.initials: I
authors.lastname: Yedidia
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives / Q000494:pharmacology; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development; D000081007:Cymenes; D005054:Eugenol / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D005798:Genes, Bacterial; D008958:Models, Molecular; D039821:Monoterpenes / Q000494:pharmacology; D009822:Oils, Volatile / Q000494:pharmacology; D044043:Pectobacterium / Q000187:drug effects* / Q000472:pathogenicity / Q000502:physiology; D010636:Phenols / Q000494:pharmacology; D010935:Plant Diseases / Q000382:microbiology / Q000517:prevention & control; D010938:Plant Oils / Q000494:pharmacology*; D011096:Polygalacturonase / Q000037:antagonists & inhibitors; D011133:Polysaccharide-Lyases / Q000037:antagonists & inhibitors; D053038:Quorum Sensing / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D017386:Sequence Homology, Amino Acid; D040681:Structural Homology, Protein; D014774:Virulence / Q000187:drug effects / Q000235:genetics / Q000502:physiology
chemical_list: D001426:Bacterial Proteins; D000081007:Cymenes; D039821:Monoterpenes; D009822:Oils, Volatile; D010636:Phenols; D010938:Plant Oils; D005054:Eugenol; C030654:N-(3-oxohexanoyl)-3-aminodihydro-2(3H)-furanone; C073316:carvacrol; D011096:Polygalacturonase; D011133:Polysaccharide-Lyases; C023911:pectate lyase; D015107:4-Butyrolactone