Project description:Comparative transcriptional profiling of the Burkholderia cenocepacia H111 wild type, the cepR mutant H111-R and the complemented cepR mutant H111-R (pBAH27).
Project description:Members of the genus Burkholderia are versatile bacteria capable of colonizing highly diverse environmental niches. In this study, we investigated the global response of the opportunistic pathogen Burkholderia cenocepacia H111 to nitrogen limitation at the transcript and protein expression level. In addition to a classical response to nitrogen starvation, including the activation of glutamine synthetase, PII proteins and the two component regulatory system ntrBC, B. cenocepacia H111 also up-regulated polyhydroxybutyrate (PHB) accumulation and exopolysaccharide (EPS) production in response to nitrogen shortage. A search for consensus sequences in promoter regions of nitrogen responsive genes identified a s54 consensus sequence. The mapping of the s54 regulon as well as the characterization of a s54 mutant suggests an important role of s54 not only in control of nitrogen metabolism, but also in virulence of this organism.
Project description:B. cenocepacia is an opportunistic human pathogen that is particularly problematic for patients suffering from cystic fibrosis (CF). In the CF lung, bacteria grow to high densities within the viscous mucus that is limited in oxygen. Pseudomonas aeruginosa, the dominant pathogen in CF patients, is known to grow and survive under oxygen-limited to anaerobic conditions by using micro-oxic respiration, denitrification and fermentative pathways. In contrast, inspection of the genome sequences of available B. cenocepacia strains suggested that B. cenocepacia is an obligate aerobic and non-fermenting bacterium. In accordance with the bioinformatics analysis, we observed that B. cenocepacia H111 is able to grow with as little as 0.1% O2 but not under strictly anoxic conditions. Phenotypic analyses revealed that H111 produced larger amounts of biofilm, pellicle and proteases under micro-oxic conditions (0.5% - 5% O2, i.e. conditions that mimic those encountered in CF lung infection), and was more resistant to several antibiotics. RNA-Seq and shotgun proteomics analyses of cultures of B. cenocepacia H111 grown under micro-oxic and aerobic conditions showed up-regulation of genes involved in the synthesis of the exopolysaccharide (EPS) cepacian as well as several proteases, two isocitrate lyases and other genes potentially important for life in micro-oxia.
Project description:B. cenocepacia is an opportunistic human pathogen that is particularly problematic for patients suffering from cystic fibrosis (CF). In the CF lung, bacteria grow to high densities within the viscous mucus that is limited in oxygen. Pseudomonas aeruginosa, the dominant pathogen in CF patients, is known to grow and survive under oxygen-limited to anaerobic conditions by using micro-oxic respiration, denitrification and fermentative pathways. In contrast, inspection of the genome sequences of available B. cenocepacia strains suggested that B. cenocepacia is an obligate aerobic and non-fermenting bacterium. In accordance with the bioinformatics analysis, we observed that B. cenocepacia H111 is able to grow with as little as 0.1% O2 but not under strictly anoxic conditions. Phenotypic analyses revealed that H111 produced larger amounts of biofilm, pellicle and proteases under micro-oxic conditions (0.5% - 5% O2, i.e. conditions that mimic those encountered in CF lung infection), and was more resistant to several antibiotics. RNA-Seq and shotgun proteomics analyses of cultures of B. cenocepacia H111 grown under micro-oxic and aerobic conditions showed up-regulation of genes involved in the synthesis of the exopolysaccharide (EPS) cepacian as well as several proteases, two isocitrate lyases and other genes potentially important for life in micro-oxia. Oxygen regulation in Burkholderia cenocepacia was investigated using RNA-Seq of cells grown under aerobic or micro-oxic conditions.
Project description:Burkholderia cenocepacia is a versatile opportunistic pathogen that survives in a wide variety of environments, which can be limited in nutrients such as nitrogen. We previously showed that B. cenocepacia sigma factor s54 played a major role in control of nitrogen assimilation and virulence. In this work, we investigated the role of the s54 enhancer binding protein NtrC in controlling the response to nitrogen limitation and virulence. RNA-Seq analyses and phenotypical analysis on a ntrC mutant strain showed that, in addition to orchestrating uptake of nitrogen sources, NtrC is also regulating exopolysaccharide (EPS) production and motility. A search for NtrC consensus sequences identified a potential binding sequence in the promoter region of gene clusters involved in EPS formation and flagellar rotation suggesting that NtrC directly controls the expression of these phenotypic traits in B. cenocepacia H111.
Project description:Members of the genus Burkholderia are versatile bacteria capable of colonizing highly diverse environmental niches. In this study, we investigated the global response of the opportunistic pathogen Burkholderia cenocepacia H111 to nitrogen limitation at the transcript and protein expression level. In addition to a classical response to nitrogen starvation, including the activation of glutamine synthetase, PII proteins and the two component regulatory system ntrBC, B. cenocepacia H111 also up-regulated polyhydroxybutyrate (PHB) accumulation and exopolysaccharide (EPS) production in response to nitrogen shortage. A search for consensus sequences in promoter regions of nitrogen responsive genes identified a s54 consensus sequence. The mapping of the s54 regulon as well as the characterization of a s54 mutant suggests an important role of s54 not only in control of nitrogen metabolism, but also in virulence of this organism. Nitrogen limitation and s54 regulon in B. cenocepacia