title: The two-component colR/S system of Pseudomonas fluorescens WCS365 plays a role in rhizosphere competence through maintaining the structure and function of the outer membrane.
abstract: Pseudomonas fluorescens strain PCL1210, a competitive tomato root tip colonization mutant of the efficient root colonizing wild type strain WCS365, is impaired in the two-component sensor-response regulator system ColR/ColS. Here we show that a putative methyltransferase/wapQ operon is located downstream of colR/colS and that this operon is regulated by ColR/ColS. Since wapQ encodes a putative lipopolysaccharide (LPS) phosphatase, the possibility was studied that the integrity of the outer membrane of PCL1210 was altered. Indeed, it was shown that mutant PCL1210 is more resistant to various chemically unrelated antibiotics which have to pass the outer membrane for their action. In contrast, the mutant is more sensitive to the LPS-binding antibiotic polymyxin B. Mutant PCL1210 loses growth in competition with its wild type when grown in tomato root exudate. Mutants in the methyltransferase/wapQ operon are also altered in their outer membrane permeability and are defective in competitive tomato root tip colonization. A model for the altered outer membrane of PCL1210 is discussed.
authors.affiliation: Institute of Biology, Leiden University, AL Leiden, The Netherlands. weert@rulbim.leidenuniv.nl
authors.forename: Sandra
authors.initials: S
authors.lastname: de Weert
authors.forename: Linda C
authors.initials: LC
authors.lastname: Dekkers
authors.forename: Wilbert
authors.initials: W
authors.lastname: Bitter
authors.forename: Sietske
authors.initials: S
authors.lastname: Tuinman
authors.forename: André H M
authors.initials: AH
authors.lastname: Wijfjes
authors.forename: Ria
authors.initials: R
authors.lastname: van Boxtel
authors.forename: Ben J J
authors.initials: BJ
authors.lastname: Lugtenberg
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics; D000667:Ampicillin / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000378:metabolism / Q000494:pharmacology; D001425:Bacterial Outer Membrane Proteins / Q000032:analysis; D018533:Biomass; D002463:Cell Membrane Permeability; D015169:Colony Count, Microbial; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics; D008070:Lipopolysaccharides / Q000032:analysis; D018551:Solanum lycopersicum / Q000382:microbiology; D008826:Microbial Sensitivity Tests; D009876:Operon; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000382:microbiology*; D011112:Polymyxin B / Q000494:pharmacology; D011551:Pseudomonas fluorescens / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D011700:Putrescine / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D001425:Bacterial Outer Membrane Proteins; D008070:Lipopolysaccharides; D000667:Ampicillin; D010744:Phosphoric Monoester Hydrolases; D011112:Polymyxin B; D011700:Putrescine