title: Caenorhabditis elegans semi-automated liquid screen reveals a specialized role for the chemotaxis gene cheB2 in Pseudomonas aeruginosa virulence.
abstract: Pseudomonas aeruginosa is an opportunistic human pathogen that causes infections in a variety of animal and plant hosts. Caenorhabditis elegans is a simple model with which one can identify bacterial virulence genes. Previous studies with C. elegans have shown that depending on the growth medium, P. aeruginosa provokes different pathologies: slow or fast killing, lethal paralysis and red death. In this study, we developed a high-throughput semi-automated liquid-based assay such that an entire genome can readily be scanned for virulence genes in a short time period. We screened a 2,200-member STM mutant library generated in a cystic fibrosis airway P. aeruginosa isolate, TBCF10839. Twelve mutants were isolated each showing at least 70% attenuation in C. elegans killing. The selected mutants had insertions in regulatory genes, such as a histidine kinase sensor of two-component systems and a member of the AraC family, or in genes involved in adherence or chemotaxis. One mutant had an insertion in a cheB gene homologue, encoding a methylesterase involved in chemotaxis (CheB2). The cheB2 mutant was tested in a murine lung infection model and found to have a highly attenuated virulence. The cheB2 gene is part of the chemotactic gene cluster II, which was shown to be required for an optimal mobility in vitro. In P. aeruginosa, the main player in chemotaxis and mobility is the chemotactic gene cluster I, including cheB1. We show that, in contrast to the cheB2 mutant, a cheB1 mutant is not attenuated for virulence in C. elegans whereas in vitro motility and chemotaxis are severely impaired. We conclude that the virulence defect of the cheB2 mutant is not linked with a global motility defect but that instead the cheB2 gene is involved in a specific chemotactic response, which takes place during infection and is required for P. aeruginosa pathogenicity.
authors: Laboratoire d'Ingénierie des Systèmes Macromoléculaires, UPR9027, Centre National de la Recherche Scientifique, IMM, Marseille, France.
authors: Steven
authors: S
authors: Garvis
authors: Antje
authors: A
authors: Munder
authors: Geneviève
authors: G
authors: Ball
authors: Sophie
authors: S
authors: de Bentzmann
authors: Lutz
authors: L
authors: Wiehlmann
authors: Jonathan J
authors: JJ
authors: Ewbank
authors: Burkhard
authors: B
authors: Tümmler
authors: Alain
authors: A
authors: Filloux
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001431:Bacteriological Techniques; D017173:Caenorhabditis elegans / Q000382:microbiology*; D002633:Chemotaxis / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D051379:Mice; D011552:Pseudomonas Infections / Q000235:genetics / Q000473:pathology; D011550:Pseudomonas aeruginosa / Q000235:genetics* / Q000472:pathogenicity*; D014774:Virulence
chemical_list: D001426:Bacterial Proteins; C069656:CheB protein, Bacteria