title: The Burkholderia cepacia rpoE gene is not involved in exopolysaccharide production and onion pathogenicity.
abstract: Burkholderia cepacia was originally described as the causative agent of bacterial rot of onions, and it has now emerged as an important opportunistic pathogen causing severe chronic lung infections in patients having cystic fibrosis. Burkholderia cepacia is now classified into nine very closely related species (previously designated as genomovars), all of which have been isolated from both environmental and clinical sources and are collectively known as the B. cepacia complex. The alternative extracytoplasmic function sigma factor, sigmaE, has been determined in several bacterial species as making substantial contributions to bacterial survival under stress conditions. Here, we report the identification and characterization of the rpoE gene, encoding sigmaE, of B. cepacia. It is highly similar to sigmaE of other bacteria, including Escherichia coli and Pseudomonas aeruginosa. Studies using an rpoE knockout mutant of B. cepacia revealed that many stress adaptations, including osmotic, oxidative, desiccation, carbon, and nitrogen stress, were independent of sigmaE. Similarly, biofilm formation; production of exopolysaccharides, N-acyl homoserine lactones, and several exoenzymes; and onion pathogenicity were not affected by the absence of sigmaE. In contrast, sigmaE contributed to the adaptation to heat stress and phosphate starvation.
authors.affiliation: Bateriology Group, International Centre for Genetic Engineering & Biotechnology, Italy.
authors.forename: Giulia
authors.initials: G
authors.lastname: Devescovi
authors.forename: Vittorio
authors.initials: V
authors.lastname: Venturi
mesh_terms: D000222:Adaptation, Physiological; D018441:Biofilms; D016956:Burkholderia cepacia / Q000235:genetics / Q000472:pathogenicity*; D015964:Gene Expression Regulation, Bacterial; D006360:Heat-Shock Proteins / Q000502:physiology; D008969:Molecular Sequence Data; D019697:Onions / Q000382:microbiology*; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis*; D012808:Sigma Factor / Q000502:physiology*
chemical_list: D006360:Heat-Shock Proteins; D011135:Polysaccharides, Bacterial; D012808:Sigma Factor