Project description:Pseudomonas aeruginosa is an opportunistic pathogen which causes acute and chronic infections that are difficult to treat. Comparative genomic analysis has showed a great genome diversity among P. aeruginosa clinical strains and revealed important regulatory traits during chronic adaptation. While current investigation of epigenetics of P. aeruginosa is still lacking, understanding the epigenetic regulation may provide biomarkers for diagnosis and reveal important regulatory mechanisms. The present study focused on characterization of DNA methyltransferases (MTases) in a chronically adapted P. aeruginosa clinical strain TBCF10839. Single-molecule real-time sequencing (SMRT-seq) was used to characterize the methylome of TBCF. RCCANNNNNNNTGAR and TRGANNNNNNTGC were identified as target motifs of DNA MTases, M.PaeTBCFI and M.PaeTBCFII, respectively.
Project description:PAO1 was cultured planktonically to stationary phase with 10 mM calcium and no added calcium. The transcriptional response to calcium addition was determined. Pseudomonas aeruginosa is an opportunistic human pathogen that causes severe, life threatening infections in patients with cystic fibrosis (CF), endocarditis, wounds, or with artificial implants. During CF pulmonary infections, P. aeruginosa often encounters environments where the levels of calcium (Ca2+) are elevated. Previously, we showed that P. aeruginosa responds to externally added Ca2+ through enhanced biofilm formation, increased production of several secreted virulence factors, and by developing a transient increase in the intracellular Ca2+ followed by its removal to the basal sub-micromolar level. However, the molecular mechanisms responsible for regulating Ca2+-induced virulence factor production and Ca2+ homeostasis are not known. Here, we characterized the genome-wide transcriptional response of P. aeruginosa strains PAO1 and FRD1 to elevated [Ca2+] in both planktonic cultures and in biofilms. Among the genes induced by CaCl2 in PAO1 was an operon containing the two-component regulator PA2656-PA2657 (here called carS and carR), while the closely related two-component regulators, phoPQ and pmrAB were repressed by CaCl2 addition. To identify the regulatory targets of CarSR, we constructed a deletion mutant of carR, and performed transcriptome analysis of the mutant strain at low and high [Ca2+]. Among the genes regulated by CarSR in response to CaCl2 are the predicted periplasmic OB-fold protein, PA0320 and the inner membrane-anchored five-bladed -propeller protein, PA0327. Mutations in both PA0320 and PA0327 affected Ca2+ homeostasis, reducing the ability of P. aeruginosa to export excess Ca2+. In addition, a mutation in PA0327 had a pleotrophic effect in a Ca2+-dependent manner, altering swarming motility, pyocyanin production, and tobramycin sensitivity. Overall, the results indicate that the two-component system CarSR is responsible for sensing high levels of external Ca2+, and responding through its regulatory targets that modulate Ca2+ homeostasis, surface-associated motility, and production of the virulence factor, pyocyanin.
Project description:This study addresses the impact of zinc limitation on the opportunistic human pathogen, Pseudomonas aeruginosa. Zinc limitation was assessed in the P. aeruginosa PAO1 strain using an isogenic deletion mutant lacking the periplasmic, zinc solute-binding protein, znuA (PA5498). ZnuA delivers bound zinc to its cognate ABC transporter, ZnuBC, for import into the cytoplasm. Our transcriptional analyses revealed P. aeruginosa to possess a multitude of zinc acquisition mechanisms, each of which were highly up-regulated in the zinc-deficient znuA mutant strain. P. aeruginosa also utilized zinc-independent paralogues of zinc-dependent genes to maintain cellular function under zinc limitation. Together, these data reveal the complex transcriptional response and versatility of P. aeruginosa to zinc depletion.
Project description:The role of the intracellular signaling molecule diadenosine tetraphosphate (Ap4A) has not so far been investigated in Pseudomonas aeruginosa. To fill this gap, we performed RNA sequencing (RNA-seq) analysis to compare the transcriptome of the reference strain P. aeruginosa PAO1 and an isogenic deletion mutant (ΔapaH) which is deficient in the Ap4A hydrolysing enzyme ApaH and accumulates high intracellular levels of Ap4A.
Project description:Pseudomonas aeruginosa (P. aeruginosa) lung infection is a significant cause of mortality in patients with cystic fibrosis (CF). Most CF patients acquire unique P. aeruginosa strains from the environment; however clonal strains have been identified in CF communities in several countries. Two clonal strains infect 10% to 40% of patients in three CF clinics in mainland eastern Australia. The expression profiles of four planktonically-grown isolates of one Australian clonal strain (AES-2), and four non–clonal CF P. aeruginosa isolates were compared to each other and to the reference strain PAO1 using the Affymetrix P. aeruginosa PAO1 genome array, to gain insight into properties mediating the enhanced infectivity of AES-1. The isolates were subsequently grown as 3-day old biofilms and similarly extracted for RNA and compared as above. Data analysis was carried out using BIOCONDUCTOR software. Keywords: Comparative strain hybridization
Project description:Pseudomonas aeruginosa is an opportunistic pathogen which causes acute and chronic infections that are difficult to treat. Comparative genomic analysis has showed a great genome diversity among P. aeruginosa clinical strains and revealed important regulatory traits during chronic adaptation. While current investigation of epigenetics of P. aeruginosa is still lacking, understanding the epigenetic regulation may provide biomarkers for diagnosis and reveal important regulatory mechanisms. The present study focused on characterization of DNA methyltransferases (MTases) in a chronically adapted P. aeruginosa clinical strain TBCF10839. Single-molecule real-time sequencing (SMRT-seq) was used to characterize the methylome of TBCF. RCCANNNNNNNTGAR and TRGANNNNNNTGC were identified as target motifs of DNA MTases, M.PaeTBCFI and M.PaeTBCFII, respectively. LC-MS/MS analysis of DNA methylation was employed to verify the MTase activities. Transcriptomic analysis showed that ΔM.PaeTBCFII knockout mutant significantly downregulated nitric oxide reductase (NOR) regulating and coding gene expression such as nosR and norB, which contain methylated motifs in their promoters or coding regions. These predicted target motifs in nosR and norB were not methylated in the ΔM.PaeTBCFII knockout mutant. ΔM.PaeTBCFII exhibited reduced intercellular survival capacity in NO-producing RAW 264.7 macrophages and attenuated virulence in Galleria mellonella infection model. While the complemented strain recovered these defective phenotypes. Further phylogenetic analysis demonstrated that homologs of M.PaeTBCFII is frequently exists in P. aeruginosa sp as well as other bacteria species. Our work therefore provided new insights on the relationship between DNA methylation, NO detoxification, and bacterial virulence, laying a foundation for further exploring the molecular mechanism of DNA methyltransferase in regulating the pathogenicity of P. aeruginosa.
Project description:To gain insights into the mechanisms by which RC301 compensates for the deficiency in the NPR-1 controlled immune and behavioral responses of strain DA650, we determine the whole-genome expression profile of these two strains upon exposure to Pseudomonas aeruginosa strain PA14
Project description:Analysis of a SigX knockout mutant of Pseudomonas aeruginosa H103 strain in minimal medium with glucose as carbon source (M9G). SigX, one of the 19 extra-cytoplasmic function sigma factors of P. aeruginosa, was only known to be involved in transcription of the gene encoding the major outer membrane protein OprF in Pseudomonas aeruginosa. Deletion of the ECF sigma factor sigX gene provide insights into the SigX role in several virulence and biofilm- related phenotypes in Pseudomonas aeruginosa.