title: The Systematic Investigation of the Quorum Sensing System of the Biocontrol Strain Pseudomonas chlororaphis subsp. aurantiaca PB-St2 Unveils aurI to Be a Biosynthetic Origin for 3-Oxo-Homoserine Lactones.
abstract: The shoot endophytic biocontrol strain Pseudomonas chlororaphis subsp. aurantiaca PB-St2 produces a wide range of exoproducts, including enzymes and antibiotics. The production of exoproducts is commonly tightly regulated. In order to get a deeper insight into the regulatory network of PB-St2, the strain was systematically investigated regarding its quorum sensing systems, both on the genetic and metabolic level. The genome analysis of PB-St2 revealed the presence of four putative acyl homoserine lactone (AHL) biosynthesis genes: phzI, csaI, aurI, and hdtS. LC-MS/MS analyses of the crude supernatant extracts demonstrated that PB-St2 produces eight AHLs. In addition, the concentration of all AHL derivatives was quantified time-resolved in parallel over a period of 42 h during the growth of P. aurantiaca PB-St2, resulting in production curves, which showed differences regarding the maximum levels of the AHLs (14.6 nM- 1.75 μM) and the production period. Cloning and heterologous overexpression of all identified AHL synthase genes in Escherichia coli proved the functionality of the resulting synthases PhzI, CsaI, and AurI. A clear AHL production pattern was assigned to each of these three AHL synthases, while the HdtS synthase did not lead to any AHL production. Furthermore, the heterologous expression study demonstrated unequivocally and for the first time that AurI directs the synthesis of two 3-oxo-AHLs.
authors.affiliation: Department of Pharmaceutical Biology, Pharmaceutical Institute, University of Tuebingen, Tuebingen, Germany.|German Centre for Infection Research (DZIF), Partner site Tuebingen, Tuebingen, Germany.
authors.forename: Judith S
authors.initials: JS
authors.lastname: Bauer
authors.affiliation: Department of Pharmaceutical Biology, Pharmaceutical Institute, University of Tuebingen, Tuebingen, Germany.|German Centre for Infection Research (DZIF), Partner site Tuebingen, Tuebingen, Germany.
authors.forename: Nils
authors.initials: N
authors.lastname: Hauck
authors.affiliation: Department of Pharmaceutical Biology, Pharmaceutical Institute, University of Tuebingen, Tuebingen, Germany.|German Centre for Infection Research (DZIF), Partner site Tuebingen, Tuebingen, Germany.
authors.forename: Lisa
authors.initials: L
authors.lastname: Christof
authors.affiliation: Department of Biological Sciences, Forman Christian College (A Chartered University), Lahore, Pakistan.
authors.forename: Samina
authors.initials: S
authors.lastname: Mehnaz
authors.affiliation: Department of Pharmaceutical Biology, Pharmaceutical Institute, University of Tuebingen, Tuebingen, Germany.|German Centre for Infection Research (DZIF), Partner site Tuebingen, Tuebingen, Germany.
authors.forename: Bertolt
authors.initials: B
authors.lastname: Gust
authors.affiliation: Department of Pharmaceutical Biology, Pharmaceutical Institute, University of Tuebingen, Tuebingen, Germany.|German Centre for Infection Research (DZIF), Partner site Tuebingen, Tuebingen, Germany.
authors.forename: Harald
authors.initials: H
authors.lastname: Gross
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000096:biosynthesis; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D002853:Chromatography, Liquid; D055432:Metabolomics / Q000379:methods; D005810:Multigene Family; D010619:Phenazines / Q000378:metabolism; D011549:Pseudomonas / Q000502:physiology*; D000070096:Pseudomonas chlororaphis / Q000502:physiology; D053038:Quorum Sensing / Q000235:genetics; D053719:Tandem Mass Spectrometry
chemical_list: D001426:Bacterial Proteins; D010619:Phenazines; C088386:homoserine lactone; D015107:4-Butyrolactone