title: Genetic and functional characterization of cyclic lipopeptide white-line-inducing principle (WLIP) production by rice rhizosphere isolate Pseudomonas putida RW10S2.
abstract: The secondary metabolite mediating the GacS-dependent growth-inhibitory effect exerted by the rice rhizosphere isolate Pseudomonas putida RW10S2 on phytopathogenic Xanthomonas species was identified as white-line-inducing principle (WLIP), a member of the viscosin group of cyclic lipononadepsipeptides. WLIP producers are commonly referred to by the taxonomically invalid name "Pseudomonas reactans," based on their capacity to reveal the presence of a nearby colony of Pseudomonas tolaasii by inducing the formation of a visible precipitate ("white line") in agar medium between both colonies. This phenomenon is attributed to the interaction of WLIP with a cyclic lipopeptide of a distinct structural group, the fungitoxic tolaasin, and has found application as a diagnostic tool to identify tolaasin-producing bacteria pathogenic to mushrooms. The genes encoding the WLIP nonribosomal peptide synthetases WlpA, WlpB, and WlpC were identified in two separate genomic clusters (wlpR-wlpA and wlpBC) with an operon organization similar to that of the viscosin, massetolide, and entolysin biosynthetic systems. Expression of wlpR is dependent on gacS, and the encoded regulator of the LuxR family (WlpR) activates transcription of the biosynthetic genes and the linked export genes, which is not controlled by the RW10S2 quorum-sensing system PmrR/PmrI. In addition to linking the known phenotypes of white line production and hemolytic activity of a WLIP producer with WLIP biosynthesis, additional properties of ecological relevance conferred by WLIP production were identified, namely, antagonism against Xanthomonas and involvement in swarming and biofilm formation.
authors.affiliation: Centre of Microbial and Plant Genetics, KU Leuven, Heverlee, Belgium.
authors.forename: Hassan
authors.initials: H
authors.lastname: Rokni-Zadeh
authors.forename: Wen
authors.initials: W
authors.lastname: Li
authors.forename: Aminael
authors.initials: A
authors.lastname: Sanchez-Rodriguez
authors.forename: Davy
authors.initials: D
authors.lastname: Sinnaeve
authors.forename: Jef
authors.initials: J
authors.lastname: Rozenski
authors.forename: José C
authors.initials: JC
authors.lastname: Martins
authors.forename: René
authors.initials: R
authors.lastname: De Mot
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics; D018441:Biofilms / Q000254:growth & development; D003470:Culture Media; D015964:Gene Expression Regulation, Bacterial; D055666:Lipopeptides / Q000096:biosynthesis* / Q000235:genetics; D009876:Operon; D012275:Oryza / Q000382:microbiology*; D010453:Peptide Synthases / Q000134:cerebrospinal fluid / Q000235:genetics; D010456:Peptides, Cyclic / Q000096:biosynthesis* / Q000235:genetics; D016958:Pseudomonas putida / Q000235:genetics / Q000254:growth & development / Q000378:metabolism* / Q000502:physiology; D058441:Rhizosphere
chemical_list: D001426:Bacterial Proteins; D003470:Culture Media; D055666:Lipopeptides; D010456:Peptides, Cyclic; D010453:Peptide Synthases; C104385:non-ribosomal peptide synthase