title: Thioquinolobactin, a Pseudomonas siderophore with antifungal and anti-Pythium activity.
abstract: Under conditions of iron limitation Pseudomonas fluorescens ATCC 17400 produces two siderophores, pyoverdine, and a second siderophore quinolobactin, which itself results from the hydrolysis of the unstable molecule 8-hydroxy-4-methoxy-2-quinoline thiocarboxylic acid (thioquinolobactin). Pseudomonas fluorescens ATCC 17400 also displays a strong in vitro antagonism against the Oomycete Pythium, which is repressed by iron, suggesting the involvement of a siderophore(s). While a pyoverdine-negative mutant retains most of its antagonism, a thioquinolobactin-negative mutant only slowed-down Pythium growth, and a double pyoverdine-, thioquinolobactin-negative mutant, which does not produce any siderophore, totally lost its antagonism against Pythium. The siderophore thioquinolobactin could be purified and identified from spent medium and showed anti-Pythium activity, but it was quickly hydrolysed to quinolobactin, which we showed has no antimicrobial activity. Analysis of antagonism-affected transposon mutants revealed that genes involved in haem biosynthesis and sulfur assimilation are important for the production of thioquinolobactin and the expression of antagonism.
authors.affiliation: Laboratory of Microbial Interactions, Department of Molecular and Cellular Interactions, Flanders Interuniversity Institute for Biotechnology, Vrije Universiteit Brussel, Building E, Pleinlaan 2, 1050 Brussels, Belgium.
authors.forename: Sandra
authors.initials: S
authors.lastname: Matthijs
authors.forename: Kourosch Abbaspour
authors.initials: KA
authors.lastname: Tehrani
authors.forename: George
authors.initials: G
authors.lastname: Laus
authors.forename: Robert W
authors.initials: RW
authors.lastname: Jackson
authors.forename: Richard M
authors.initials: RM
authors.lastname: Cooper
authors.forename: Pierre
authors.initials: P
authors.lastname: Cornelis
mesh_terms: D000935:Antifungal Agents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D004251:DNA Transposable Elements; D006418:Heme / Q000096:biosynthesis; D006868:Hydrolysis; D008969:Molecular Sequence Data; D009154:Mutation; D009842:Oligopeptides / Q000235:genetics / Q000378:metabolism; D010641:Phenotype; D011551:Pseudomonas fluorescens / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011775:Pythium / Q000187:drug effects* / Q000254:growth & development; D011804:Quinolines / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology*; D017262:Siderophores / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D013455:Sulfur / Q000378:metabolism
chemical_list: D000935:Antifungal Agents; D004251:DNA Transposable Elements; D009842:Oligopeptides; D011804:Quinolines; D017262:Siderophores; C404845:quinolobactin; C518370:thioquinolobactin; D006418:Heme; D013455:Sulfur; C042453:pyoverdin