Mucoidy, or overproduction of the exopolysaccharide known as alginate, in Pseudomonas aeruginosa is a poor prognosticator for lung infections in cystic fibrosis. Mutation of the anti-sigma factor MucA is a well-accepted mechanism for mucoid conversion. However, certain clinical mucoid strains of P. aeruginosa have a wild-type (wt) mucA. Here, we describe a loss-of-function mutation in kinB that...

Vfr, a global regulator of Pseudomonas aeruginosa virulence factors, is a homologue of the Escherichia coli cAMP receptor protein, CRP. Vfr is 91% similar to CRP and maintains many residues important for CRP to bind cAMP, bind DNA, and interact with RNA polymerase at target promoters. While vfr can complement an E. coli crp mutant in beta-galactosidase production, tryptophanase production and c...

BACKGROUND The purpose of this study was to evaluate the virulence profiles of Pseudomonas aeruginosa clinical strains recently isolated from patients hospitalized for chronic leg ulcers in the Dermatology Department of Central Military Emergency University Hospital "Carol Davila", Bucharest, Romania. METHODS The phenotypic screening evaluated eight soluble virulence factors (haemolysins, lec...

Extracellular polymers can facilitate the non-specific attachment of bacteria to surfaces and hold together developing biofilms. This study was undertaken to qualitatively and quantitatively compare the architecture of biofilms produced by Pseudomonas aeruginosa strain PAO1 and its alginate-overproducing (mucA22) and alginate-defective (algD) variants in order to discern the role of alginate in...

The exopolysaccharide alginate is a major virulence factor in the pathogenicity of Pseudomonas aeruginosa infecting the lungs of cystic fibrosis (CF) patients. Alginate synthesis by P. aeruginosa is believed to occur in response to environmental signals present in the CF lung. Transcription of a critical alginate biosynthetic gene, algD, is triggered by environmental signals and is known to be ...

The response regulator AlgR is required for both alginate biosynthesis and type IV fimbria-mediated twitching motility in Pseudomonas aeruginosa. In this study, the roles of AlgR signal transduction and phosphorylation in twitching motility and biofilm formation were examined. The predicted phosphorylation site of AlgR (aspartate 54) and a second aspartate (aspartate 85) in the receiver domain ...

Alginate is an important virulence factor for Pseudomonas aeruginosa during infection of the lungs of cystic fibrosis patients. The genes encoding enzymes for alginate production by P. aeruginosa are normally silent. They are activated in response to several environmental conditions, including high osmolarity, exposure to ethanol, or long-term growth under conditions of nutrient deprivation. Se...