Alginate production in mucoid (MucA-defective) Pseudomonas aeruginosa is dependent upon several transcriptional regulators, including AlgB, a two-component response regulator belonging to the NtrC family. This role of AlgB was apparently independent of its sensor kinase, KinB, and even the N-terminal phosphorylation domain of AlgB was dispensable for alginate biosynthetic gene (i.e., algD opero...

Pulmonary infection by mucoid, alginate producing, Pseudomonas aeruginosa is a major complication in patients suffering from cystic fibrosis (CF). To analyze the mechanisms leading to the emergence of mucoid P. aeruginosa in CF lungs, control of the algD gene coding for GDPmannose dehydrogenase was studied. Transcriptional activation of algD was shown to be necessary for alginate production. Se...

Inactivation of Pseudomonas aeruginosa phpA, encoding a putative leucine aminopeptidase, results in increased transcription of algD. The homologous protein in Escherichia coli, PepA, is multifunctional, possessing independent aminopeptidase and DNA-binding activities. Here we provide in vitro evidence that PhpA is an aminopeptidase and show that this activity is the relevant property with regar...

Chronic lung infection with mucoid, alginate-producing strains of Pseudomonas aeruginosa is a major cause of mortality in cystic fibrosis (CF) patients. Transcriptional activation of the P. aeruginosa algD gene, which encodes GDPmannose dehydrogenase, is essential for alginate synthesis. Activation of algD is dependent on the product of the algR gene. Sequence homology between the P. aeruginosa...

The conversion to mucoid, exopolysaccharide alginate-overproducing phenotype in Pseudomonas aeruginosa during chronic respiratory infections in cystic fibrosis patients occurs via mutations that activate the alternative sigma factor AlgU (sigmaE). In this study, we demonstrate that conversion to mucoidy can be caused via a second, algU-independent pathway, in which alginate production and trans...

Both Pseudomonas aeruginosa and the phytopathogen P. syringae produce the exopolysaccharide alginate. However, the environmental signals that trigger alginate gene expression in P. syringae are different from those in P. aeruginosa with copper being a major signal in P. syringae. In P. aeruginosa, the alternate sigma factor encoded by algT (sigma22) and the response regulator AlgR1 are required...

Chromosomal DNA from group I Pseudomonas species, Azotobacter vinelandii, Azomonas macrocytogens, Xanthomonas campestris, Serpens flexibilis, and three enteric bacteria was screened for sequences homologous to four Pseudomonas aeruginosa alginate (alg) genes (algA, pmm, algD, and algR1). All the group I Pseudomonas species tested (including alginate producers and nonproducers) contained sequenc...

Transcription of the Azotobacter vinelandii algD gene, which encodes GDP-mannose dehydrogenase (the rate-limiting enzyme of alginate synthesis), starts from three sites: p1, p2, and p3. The sensor kinase GacS, a member of the two-component regulatory system, is required for transcription of algD from its three sites during the stationary phase. Here we show that algD is expressed constitutively...

Transcription of the Azotobacter vinelandii algD gene, which encodes GDP-mannose dehydrogenase (the rate-limiting enzyme of alginate synthesis), starts from three sites: p1, p2, and p3. The sensor kinase GacS, a member of the two-component regulatory system, is required for transcription of algD from its three sites during the stationary phase. Here we show that algD is expressed constitutively...

Strains of Pseudomonas aeruginosa isolated from the respiratory tracts of patients with cystic fibrosis often display a mucoid morphology due to high levels of expression of the exopolysaccharide alginate. The response regulator AlgB is required for full transcription of the alginate biosynthetic operon. Repeated attempts to demonstrate a direct interaction between AlgB and the promoter region ...