Sialic acid relieves RetS-dependent inhibition of GacS to induce a chronic infection state of Pseudomonas aeruginosa
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ABSTRACT:
ORGANISM(S): Pseudomonas aeruginosa
PROVIDER: GSE111903 | GEO | 2019/03/30
REPOSITORIES: GEO
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Project description:Sialic acid relieves RetS-dependent inhibition of GacS to induce a chronic infection state of Pseudomonas aeruginosa
| PRJNA438513 | ENA
Project description:Pseudomonas species are ubiquitous in plant-associated environments and produce an array of volatiles, enzymes and antimicrobials. The biosynthesis of many metabolites is regulated by the GacS/GacA two-component regulatory system. Transcriptome analysis of Pseudomonas fluorescens SBW25 revealed that 702 genes were differentially regulated (fold change>4, P<0.0001) in a gacS::Tn5 mutant, with 300 and 402 genes up- and down-regulated, respectively. Genes that were significantly down-regulated are involved in viscosin biosynthesis (viscABC), protease production (aprA), motility, biofilm formation, and secretory systems. Genes that were significantly up-regulated are involved in siderophore biosynthesis and oxidative stress. In contrast to previous studies with gac-mutants of other Pseudomonas species/strains, the gacS mutant of SBW25 inhibited growth of oomycete, fungal and bacterial pathogens significantly more than parental strain SBW25. A potential candidate for this enhanced antimicrobial activity was a large nonribosomal peptide synthetase (NRPS) gene cluster predicted to encode for an 8-amino-acid ornicorrugatin-like peptide. Site-directed mutagenesis of an NRPS gene in this cluster, however, did not lead to a reduction in the antimicrobial activity of the gacS mutant. Collectively these results indicate that a mutation in the GacS/GacA regulatory system causes major transcriptional changes in P. fluorescens SBW25 and significantly enhances its antimicrobial activities by yet unknown mechanisms.
2013-06-17 | GSE43443 | GEO
Project description:Pseudomonas species are ubiquitous in plant-associated environments and produce an array of volatiles, enzymes and antimicrobials. The biosynthesis of many metabolites is regulated by the GacS/GacA two-component regulatory system. Transcriptome analysis of Pseudomonas fluorescens SBW25 revealed that 702 genes were differentially regulated (fold change>4, P<0.0001) in a gacS::Tn5 mutant, with 300 and 402 genes up- and down-regulated, respectively. Genes that were significantly down-regulated are involved in viscosin biosynthesis (viscABC), protease production (aprA), motility, biofilm formation, and secretory systems. Genes that were significantly up-regulated are involved in siderophore biosynthesis and oxidative stress. In contrast to previous studies with gac-mutants of other Pseudomonas species/strains, the gacS mutant of SBW25 inhibited growth of oomycete, fungal and bacterial pathogens significantly more than parental strain SBW25. A potential candidate for this enhanced antimicrobial activity was a large nonribosomal peptide synthetase (NRPS) gene cluster predicted to encode for an 8-amino-acid ornicorrugatin-like peptide. Site-directed mutagenesis of an NRPS gene in this cluster, however, did not lead to a reduction in the antimicrobial activity of the gacS mutant. Collectively these results indicate that a mutation in the GacS/GacA regulatory system causes major transcriptional changes in P. fluorescens SBW25 and significantly enhances its antimicrobial activities by yet unknown mechanisms. This expression study used total RNA recovered from four separate wild-type cultures of Pseudomonas fluorescens SBW25 and four separate cultures of the gacS mutant. Expression design was based on the updated genome sequence of Pseudomonas fluorescens SBW25, NC_012660.1 and associated plasmid pQBR0476 with nineteen 60-mer probe per gene. Each probe is replicated 3 times. The design includes random GC and other control probes.
2013-06-17 | E-GEOD-43443 | biostudies-arrayexpress
Project description:The GacS/GacA two component regulatory system globally activates the production of secondary metabolites including phenazines in Pseudomonas chlororaphis 30-84. To better understand the regulatory role of the Gac system, we conducted RNA-seq analyses to determine the regulon of the response regulator GacA. Transcriptome analyses identified over 700 genes differentially regulated by GacA. Consistent with our previous findings, phenazine biosynthetic genes were significantly down-regulated in a gacA mutant. The expression levels of phenazine regulatory genes such as phzI, phzR, iopA, iopB, rpoS and pip were also decreased. Moreover, the expression of three none-coding RNAs (ncRNAs) including rsmX, rsmY and rsmZ was significantly decreased by gacA mutation consistent with the presence of GacA binding sites in their promoters. Our results also demonstrated that over-expression of rsmZ from a non-gac regulated promoter resulted in the restoration of AHL and phenazine production as well as the expression of other secondary metabolites in gac mutants. The role of RsmA and RsmE in phenazine production was also investigated. Over-expression of rsmE, but not rsmA, resulted in decreased AHL production and phenazine gene expression in P. chlororaphis. Consistently, a mutation in rsmE bypassed the requirement of GacA in phenazine gene expression. On the contrary, constitutive expression of the phzI/phzR quorum sensing system was not able to rescue phenazine production in the gacA mutant indicating the direct impact of Gac system on the transcript stability of phenazine biosynthetic genes. Together, these results indicate that the Gac system regulates phenazine production at multiple levels and exerts its positive effect on AHL and phenazine biosynthesis via RsmZ and RsmE. A model is proposed to illustrate the GacA regulon in P. chlororaphis 30-84. A total of 6 samples were analyzed in AB medium + 2% casamino acids, Pseudomonas chlororaphis wild type strain (3 replicates); Pseudomonas chlororaphis gacA mutant (3 replicates).
2014-12-11 | E-GEOD-43083 | biostudies-arrayexpress
Project description:The GacS/GacA two component regulatory system globally activates the production of secondary metabolites including phenazines in Pseudomonas chlororaphis 30-84. To better understand the regulatory role of the Gac system, we conducted RNA-seq analyses to determine the regulon of the response regulator GacA. Transcriptome analyses identified over 700 genes differentially regulated by GacA. Consistent with our previous findings, phenazine biosynthetic genes were significantly down-regulated in a gacA mutant. The expression levels of phenazine regulatory genes such as phzI, phzR, iopA, iopB, rpoS and pip were also decreased. Moreover, the expression of three none-coding RNAs (ncRNAs) including rsmX, rsmY and rsmZ was significantly decreased by gacA mutation consistent with the presence of GacA binding sites in their promoters. Our results also demonstrated that over-expression of rsmZ from a non-gac regulated promoter resulted in the restoration of AHL and phenazine production as well as the expression of other secondary metabolites in gac mutants. The role of RsmA and RsmE in phenazine production was also investigated. Over-expression of rsmE, but not rsmA, resulted in decreased AHL production and phenazine gene expression in P. chlororaphis. Consistently, a mutation in rsmE bypassed the requirement of GacA in phenazine gene expression. On the contrary, constitutive expression of the phzI/phzR quorum sensing system was not able to rescue phenazine production in the gacA mutant indicating the direct impact of Gac system on the transcript stability of phenazine biosynthetic genes. Together, these results indicate that the Gac system regulates phenazine production at multiple levels and exerts its positive effect on AHL and phenazine biosynthesis via RsmZ and RsmE. A model is proposed to illustrate the GacA regulon in P. chlororaphis 30-84.
2014-12-11 | GSE43083 | GEO
Project description:The GacS/GacA signal transduction system is a central regulator in Pseudomonas spp., including the biological control strain P. fluorescens Pf-5, in which GacS/GacA controls the production of secondary metabolites and exoenzymes that suppress plant pathogens. A whole genome oligonucleotide microarray was developed for Pf-5 and used to assess the global transcriptomic consequences of a gacA mutation in P. fluorescens Pf-5. In cultures at the transition from exponential to stationary growth phase, GacA significantly influenced transcript levels of 632 genes, representing more than 10% of the 6147 annotated genes in the Pf-5 genome. Transcripts of genes involved in the production of hydrogen cyanide, the antibiotic pyoluteorin, and the extracellular protease AprA were at a low level in the gacA mutant, whereas those functioning in siderophore production and other aspects of iron homeostasis were significantly higher in the gacA mutant than in wild-type Pf-5. Notable effects of gacA inactivation were also observed in the transcription of genes encoding components of a type VI secretion system and cytochrome C oxidase subunits. Two novel gene clusters expressed under the control of gacA were identified from transcriptome analysis, and we propose global-regulator-based genome mining as an approach to decipher the secondary metabolome of Pseudomonas spp.
2010-03-04 | GSE16898 | GEO
Project description:The biocontrol agent Pseudomonas chlororaphis PA23 protects canola (Brassica napus) against infection by the necrotrophic fungus Sclerotinia sclerotiorum. Production of PA23 secondary metabolites is governed by a complex regulatory pathway that includes the GacA/GacS two component system, the PhzI/PhzR quorum-sensing system, and a novel LysR-type transcriptional regulator, called PtrA. Through RNA-sequencing, transcriptomic profiles of PA23-WT, two quorum sensing-deficient strains, PA23-AHL and PA23-phzR, and regulatory mutants PA23-gacA, PA23-gacS and PA23-ptrA were generated allowing elucidation of the PhzRI, Gac and PtrA regulons of P. chlororaphis PA23.
2018-05-26 | GSE114924 | GEO
Project description:Pseudomonas syringae pv. phaseolicola is the causal agent of halo blight disease of beans (Phaseolus vulgaris L.), which is characterized by water-soaked lesions surrounded by a chlorotic halo resulting from the action of a non-host-specific toxin known as phaseolotoxin, that inhibits the enzyme ornithine carbamoyltransferase involved in the arginine biosynthesis pathway. It was previously reported that genes within the Pht cluster were involved in the regulation and synthesis of phaseolotoxin. The GacS/GacA two component signal transduction system controls important pathogenicity and virulence mechanisms in several Gram-negative bacteria. In the present study we hybridized a genomic microarray of P. syringae pv. phaseolicola NPS3121 to compare transcriptional profiles from wild type strain and a gacA- null mutant with a Tox- 11 phenotype. Results show that GacA controls expression of genes within the Pht cluster as well as another group of clustered genes located in a 13 different region in the bacterial chromosome that contains at least one gene unambiguously shown to be directly involved in phaseolotoxin biosynthesis. Results suggest that this cluster is a new pathogenicity island containing genes whose regulation is also under GacA regulatory cascade and it will require further investigation to determine gene functions and their relationship to virulence mechanisms
2009-07-20 | GSE16632 | GEO
Project description:To investigate the influence of GacA on the genome-wide transcription of the rhizobacterium P. aeruginosa M18, DNA microarray experiments were carried out to compare the transcriptional profile of M18 with that of the gacA mutant grown to the early stationary phase (OD600 = 5.0 ~ 5.5) in KMB media. When compared with the M18 parental strain, the transcriptomic profile of gacA mutant revealed the significantly differential expression (increased or decreased by at least 2-fold as well as p-value < 0.05) of 839 genes, which represent approximately 15% of all 5696 annotated genes in the M18 genome. Of these 839 genes, 472 were downregulated and 367 genes were upregulated by the gacA mutation.
2013-06-07 | GSE43655 | GEO
Project description:Pseudomonas syringae pv. phaseolicola is the causal agent of halo blight disease of beans (Phaseolus vulgaris L.), which is characterized by water-soaked lesions surrounded by a chlorotic halo resulting from the action of a non-host-specific toxin known as phaseolotoxin, that inhibits the enzyme ornithine carbamoyltransferase involved in the arginine biosynthesis pathway. It was previously reported that genes within the Pht cluster were involved in the regulation and synthesis of phaseolotoxin. The GacS/GacA two component signal transduction system controls important pathogenicity and virulence mechanisms in several Gram-negative bacteria. In the present study we hybridized a genomic microarray of P. syringae pv. phaseolicola NPS3121 to compare transcriptional profiles from wild type strain and a gacA- null mutant with a Tox- 11 phenotype. Results show that GacA controls expression of genes within the Pht cluster as well as another group of clustered genes located in a 13 different region in the bacterial chromosome that contains at least one gene unambiguously shown to be directly involved in phaseolotoxin biosynthesis. Results suggest that this cluster is a new pathogenicity island containing genes whose regulation is also under GacA regulatory cascade and it will require further investigation to determine gene functions and their relationship to virulence mechanisms Transcriptional profiles of a P. syringae pv. phaseolicola NPS3121 null gacA mutant were compared to those of the wild-type strain. Cultures were grown in minimal medium at 18°C (which is the temperature at which phaseolotoxin is produced and the bacteria achieves full virulence) and harvested during the late log phase of the exponential growth. RNA from three biological replicates and each with two technical replicates were hybridize to control variation that might affect data interpretation.
2010-05-16 | E-GEOD-16632 | biostudies-arrayexpress