Pseudomonas aeruginosa in cystic fibrosis: role of mucC in the regulation of alginate production and stress sensitivity

Boucher, J C; Schurr, Michael J.; Yu, Hongwei D.; Rowen, Donald W.; Deretić, Vojo

doi:10.1099/00221287-143-11-3473

Cited by 64 publications

(55 citation statements)

References 39 publications

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“…The regulation of alginate is mediated by a hierarchy of proteins, including those encoded by the algTmucABCD operon. The mucC gene encodes a negative regulator for alginate biosynthesis (8,46), and its expression was found here to be surface induced in P. putida.…”

Section: Discussionmentioning

confidence: 99%

Characterization of Phenotypic Changes in Pseudomonas putida in Response to Surface-Associated Growth

2001

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The formation of complex bacterial communities known as biofilms begins with the interaction of planktonic cells with a surface. A switch between planktonic and sessile growth is believed to result in a phenotypic change in bacteria. In this study, a global analysis of physiological changes of the plant saprophyte Pseudomonas putida following 6 h of attachment to a silicone surface was carried out by analysis of protein profiles and by mRNA expression patterns. Two-dimensional (2-D) gel electrophoresis revealed 15 proteins that were up-regulated following bacterial adhesion and 30 proteins that were down-regulated. N-terminal sequence analyses of 11 of the down-regulated proteins identified a protein with homology to the ABC transporter, PotF; an outer membrane lipoprotein, NlpD; and five proteins that were homologous to proteins involved in amino acid metabolism. cDNA subtractive hybridization revealed 40 genes that were differentially expressed following initial attachment of P. putida. Twenty-eight of these genes had known homologs. As with the 2-D gel analysis, NlpD and genes involved in amino acid metabolism were identified by subtractive hybridization and found to be down-regulated following surface-associated growth. The gene for PotB was up-regulated, suggesting differential expression of ABC transporters following attachment to this surface. Other genes that showed differential regulation were structural components of flagella and type IV pili, as well as genes involved in polysaccharide biosynthesis. Immunoblot analysis of PilA and FliC confirmed the presence of flagella in planktonic cultures but not in 12-or 24-h biofilms. In contrast, PilA was observed in 12-h biofilms but not in planktonic culture. Recent evidence suggests that quorum sensing by bacterial homoserine lactones (HSLs) may play a regulatory role in biofilm development. To determine if similar protein profiles occurred during quorum sensing and during early biofilm formation, HSLs extracted from P. putida and pure C 12 -HSL were added to 6-h planktonic cultures of P. putida, and cell extracts were analyzed by 2-D gel profiles. Differential expression of 16 proteins was observed following addition of HSLs. One protein, PotF, was found to be down-regulated by both surface-associated growth and by HSL addition. The other 15 proteins did not correspond to proteins differentially expressed by surface-associated growth. The results presented here demonstrate that P. putida undergoes a global change in gene expression following initial attachment to a surface. Quorum sensing may play a role in the initial attachment process, but other sensory processes must also be involved in these phenotypic changes.

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Section: Discussionmentioning

confidence: 99%

Characterization of Phenotypic Changes in Pseudomonas putida in Response to Surface-Associated Growth

2001

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“…MucB is also a negative regulator that binds to MucA and forms a signal transduction complex that normally keeps the AlgT transcriptional activity low Mathee et al, 1997;Rowen & Deretic, 2000). The function of MucC is generally unknown but it has been reported as being both a positive and a negative regulator (Boucher et al, 1997a). MucD is a close homologue of Escherichia coli HtrA (DegP), a periplasmic serine protease that is involved in the proteolysis of abnormal proteins and is required for resistance to oxidative and heat stress (Boucher et al, 1997b).…”

Section: Introductionmentioning

confidence: 99%

Investigation of the algT operon sequence in mucoid and non-mucoid Pseudomonas aeruginosa isolates from 115 Scandinavian patients with cystic fibrosis and in 88 in vitro non-mucoid revertants

et al. 2008

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Investigation of the algT operon sequence in mucoid and non-mucoid Pseudomonas aeruginosa isolates from 115 Scandinavian patients with cystic fibrosis and in 88 in vitro non-mucoid revertants Pseudomonas aeruginosa is the dominant pathogen causing chronic lung infections in patients with cystic fibrosis (CF). After an initial phase characterized by intermittent colonizations, a chronic infection is established upon conversion of P. aeruginosa from the non-mucoid to the mucoid, alginate-overproducing phenotype. During the chronic infection the isolation of both mucoid and non-mucoid isolates in CF sputum samples is very common. The purpose of the present study was to establish, by sequence analysis, the types of mutations present in the algTmucABD operon in a large number of mucoid and non-mucoid P. aeruginosa isolates from Scandinavian CF patients and in in vitro-derived non-mucoid revertants. Mucoid (83) and non-mucoid isolates (103) from 91 Scandinavian patients with chronic P. aeruginosa infection and 24 non-mucoid isolates from intermittently colonized CF patients were investigated. In addition, 88 spontaneous non-mucoid revertants obtained in vitro from nine mucoid CF isolates were also included in the study. Mutations in mucA were found in 92 % of the mucoid and in up to 70 % of the non-mucoid isolates from chronically infected patients, indicating that the majority of non-mucoid isolates are revertants. None of the non-mucoid isolates from intermittently colonized CF patients harboured mucA mutations. Although algT has been considered an important gene for secondary-site mutations responsible for reversion to non-mucoidy, only 30 % of the mucA-mutated non-mucoid CF isolates had mutations in algT. In contrast, 83 % of the in vitro-derived spontaneous non-mucoid revertants had mutations in algT, showing that in the CF lung there is a selection for non-mucoid revertants with secondary-site mutations in genes other than algT. In addition, we report, to our knowledge for the first time, loss-of-function mutations in the negative regulators mucB and mucD in CF clinical isolates. In some of the CF isolates these mutations are associated with moderate alginate production. In conclusion, most non-mucoid isolates from chronically infected CF patients are revertants and the mechanism of revertance is algT-independent in the CF lung.

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“…One alginate regulatory system involves the MucA, MucB, MucC, and MucD proteins (6,36,38,51) and their regulation of the sigma factor AlgU (AlgT) (27,37,61). Two studies examining clinical CF isolates from different locations found that a large percentage of the mucoid strains had mucA mutations.…”

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confidence: 99%

Identification of AlgR-Regulated Genes in Pseudomonas aeruginosa by Use of Microarray Analysis

et al. 2004

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The Pseudomonas aeruginosa transcriptional regulator AlgR controls a variety of different processes, including alginate production, type IV pilus function, and virulence, indicating that AlgR plays a pivotal role in the regulation of gene expression. In order to characterize the AlgR regulon, Pseudomonas Affymetrix GeneChips were used to generate the transcriptional profiles of (i) P. aeruginosa PAO1 versus its algR mutant in mid-logarithmic phase, (ii) P. aeruginosa PAO1 versus its algR mutant in stationary growth phase, and (iii) PAO1 versus PAO1 harboring an algR overexpression plasmid. Expression analysis revealed that, during mid-logarithmic growth, AlgR activated the expression of 58 genes while it repressed the expression of 37 others, while during stationary phase, it activated expression of 45 genes and repression of 14 genes. Confirmatory experiments were performed on two genes found to be AlgR repressed (hcnA and PA1557) and one AlgR-activated operon (fimU-pilVWXY1Y2). An S1 nuclease protection assay demonstrated that AlgR repressed both known hcnA promoters in PAO1. Additionally, direct measurement of hydrogen cyanide (HCN) production showed that P. aeruginosa PAO1 produced threefold-less HCN than did its algR deletion strain. AlgR also repressed transcription of two promoters of the uncharacterized open reading frame PA1557. Further, the twitching motility defect of an algR mutant was complemented by the fimTU-pilVWXY1Y2E operon, thus identifying the AlgR-controlled genes responsible for this defect in an algR mutant. This study identified four new roles for AlgR: (i) AlgR can repress gene transcription, (ii) AlgR activates the fimTU-pilVWXY1Y2E operon, (iii) AlgR regulates HCN production, and (iv) AlgR controls transcription of the putative cbb 3 -type cytochrome PA1557.

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Pseudomonas aeruginosa in cystic fibrosis: role of mucC in the regulation of alginate production and stress sensitivity

Cited by 64 publications

References 39 publications

Characterization of Phenotypic Changes in Pseudomonas putida in Response to Surface-Associated Growth

Characterization of Phenotypic Changes in Pseudomonas putida in Response to Surface-Associated Growth

Investigation of the algT operon sequence in mucoid and non-mucoid Pseudomonas aeruginosa isolates from 115 Scandinavian patients with cystic fibrosis and in 88 in vitro non-mucoid revertants

Identification of AlgR-Regulated Genes in Pseudomonas aeruginosa by Use of Microarray Analysis

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