In vitro identification of two adherence factors required for in vivo virulence of Pseudomonas fluorescens

• Published in: Microbes and infection Vol. 5; no. 13; pp. 1177 - 1187
• Main Authors: de Lima Pimenta, Andréa, Di Martino, Patrick, Le Bouder, Emmanuel, Hulen, Christian, Blight, Mark A.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier SAS 01-11-2003; Amsterdam Elsevier; Paris
• Subjects: Adherence; Animals; Bacterial Adhesion - physiology; Bacteriology; Biological and medical sciences; Cell Line; Drosophila; Drosophila melanogaster; Drosophila melanogaster - microbiology; Fibronectin; Fibronectins - metabolism; Fundamental and applied biological sciences. Psychology; GDP-mannose dehydratase; Humans; In Vitro Techniques; Life Sciences; Microbiology; Microbiology and Parasitology; Miscellaneous; Models, Animal; Mutation; Pathogenicity; Pseudomonas fluorescens; Pseudomonas fluorescens - genetics; Pseudomonas fluorescens - metabolism; Pseudomonas fluorescens - pathogenicity; Virulence - genetics; Virulence factors; Pathogenicity; Adherence; Pseudomonas fluorescens; Virulence factors; Drosophila; Fibronectin; Pseudomonadales; Fibronectin: Drosophila; Virulence; Bacteria; Pseudomonadaceae; Identification; Adhesion
• ISSN: 1286-4579; 1769-714X
• DOI: 10.1016/j.micinf.2003.09.002

By enriching a random transposon insertion bank of
Pseudomonas fluorescens for mutants affected in their adherence to the human extracellular matrix protein fibronectin, we isolated 23 adherence minus mutants. Mutants showed a defect in their ability to develop a biofilm on an abiotic surface and were impaired for virulence when tested in an in vivo virulence model in the fruit fly,
Drosophila melanogaster. Molecular characterisation of these mutants showed that the transposon insertions localised to two distinct chromosomal locations, which were subsequently cloned and characterised from two mutants. A search in the databanks identified two loci in the
Pseudomonas aeruginosa PAO1 genome with significant homology to the genes interrupted by the transposon insertions. Mutant IVC6 shows homology to
gmd, coding for the enzyme GDP-mannose dehydratase, involved in the synthesis of A-band- O-antigen-containing lipopolysaccharide (LPS). Mutant IVG7 is significantly similar to a probable outer membrane protein of strain PAO1, with no specific function attributed thus far, yet with significant homology to
Escherichia coli FadL, involved in long-chain fatty acid transport. We propose that this protein, together with LPS, is involved in the first steps of
P. fluorescens adherence leading to host colonisation. Results presented here also demonstrate the pathogenic potential of
P. fluorescens, assessed in an in vivo
Drosophila model system, correlated with its ability to adhere to the human extracellular matrix protein, fibronectin. Correlation between the mutant phenotypes with identified virulence factors and their actual role in the virulence of
P. fluorescens is discussed.