The repressor C protein, Pf4r, controls superinfection of Pseudomonas aeruginosa PAO1 by the Pf4 filamentous phage and regulates host gene expression
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ABSTRACT:
PROVIDER: PRJNA646382 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR12224945_1.fastq.gz | Fastqsanger.gz | |||
| SRR12224945_2.fastq.gz | Fastqsanger.gz | |||
| SRR12224946_1.fastq.gz | Fastqsanger.gz | |||
| SRR12224946_2.fastq.gz | Fastqsanger.gz | |||
| SRR12224947_1.fastq.gz | Fastqsanger.gz |
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Project description:It has been shown that the filamentous phage, Pf4, plays an important role in biofilm development, stress tolerance, genetic variant formation and virulence in Pseudomonas aeruginosa PAO1. These behaviours are linked to the appearance of superinfective phage variants. Here, we have investigated the molecular mechanism of superinfection as well as how the Pf4 phage can control host gene expression to modulate host behaviours. Pf4 exists as a prophage in PAO1 and encodes a homolog of the P2 phage repressor C. Through a combination of molecular techniques, ChIPseq and transcriptomic analyses, we show that repressor C (Pf4r) is the minimal factor for immunity against reinfection by Pf4 possibly through Pf4r binding to its putative promoter region, and that Pf4r also functions as a transcriptional regulator for expression of host genes. A binding motif for Pf4r was also identified. In wild type P. aeruginosa and Pfr4 complemented Pf4 deficient mutant strains, virulence factor related genes including phenazine and type VI secretion system effectors were upregulated, potentially explaining the reduced virulence of Pf4-deficient P. aeruginosa PAO1. X-ray crystal structure analysis shows that Pf4r forms symmetric homo-dimers homologous to the E.coli bacteriophage P2 RepC protein. A mutation associated with the superinfective Pf4r variant, found at the dimer interface, suggests dimer formation may be disrupted, which derepresses phage replication. This is supported by MALS analysis where the Pf4r* protein only shows monomer formation. Collectively, these data suggest the mechanism by which filamentous phages play such an important role in P. aeruginosa biofilm development.
2021-01-31 | GSE154459 | GEO
Project description:Pf4 is a filamentous bacteriophage integrated as a prophage into the genome of Pseudomonas aeruginosa PAO1. Pf4 virions can be produced without killing P. aeruginosa. Cell lysis can however occur during superinfection when Pf virions successfully infect a host lysogenized by a Pf superinfective variant. We have previously shown that infection of P. aeruginosa PAO1 with a superinfective Pf4 variant led to abolish twitching motility and to alter biofilm’s architecture. More precisely, the cells embedded into the biofilm were showing for most of them a filamentous morphology, that could be related to the activation of the cell envelope stress response involving both the AlgU and SigX extra cytoplasmic function sigma factors. Herein, we show that Pf4 variant-infection resulted also into a drastic dysregulation of 3,360 genes representing about 58% of P. aeruginosa’s genome, of which about 43% of the virulence factors encoding genes showing a down-regulation. Accordingly, Pf4 variant infection (termed Pf4*) causes in vivo reduction of P. aeruginosa virulence, decreased production of N-acyl-homoserine lactones and 2-alkyl-4-quinolones quorum sensing molecules, and related virulence factors, such as pyocyanin, elastase, and pyoverdine. In addition to virulence encoding genes, expression of genes involved in metabolism, including energy generation and iron homeostasis, was affected, suggesting further relationships between virulence and central metabolism. Altogether, these data suggest that Pf4 phage variant infection results in complex networks dysregulations, leading to reducing acute virulence in P. aeruginosa. This work contributes to the comprehension of the bacterial response to filamentous phage infection.
2022-07-05 | GSE201738 | GEO
Project description:Proteomics of PAO1 subject to Pf4 superinfection or not following 6 hours of treatment at a MOI of 10
2025-09-08 | PXD068203 |
Project description:It has been shown that the filamentous phage, Pf4, plays an important role in biofilm development, stress tolerance, genetic variant formation and virulence in Pseudomonas aeruginosa PAO1. These behaviours are linked to the appearance of superinfective phage variants. Here, we have investigated the molecular mechanism of superinfection as well as how the Pf4 phage can control host gene expression to modulate host behaviours. Pf4 exists as a prophage in PAO1 and encodes a homologue of the P2 phage repressor C and was recently named Pf4r. Through a combination of molecular techniques, ChIPseq and transcriptomic analyses, we show a critical site in repressor C (Pf4r) where a mutation in the site, 788799A>G (Ser4Pro), causes Pf4r to lose its function as the immunity factor against reinfection by Pf4. X-ray crystal structure analysis shows that Pf4r forms symmetric homo-dimers homologous to the E.coli bacteriophage P2 RepC protein. A mutation, Pf4r*, associated with the superinfective Pf4r variant, found at the dimer interface, suggests dimer formation may be disrupted, which derepresses phage replication. This is supported by multi-angle light scattering (MALS) analysis, where the Pf4r* protein only forms monomers. The loss of dimerisation also explains the loss of Pf4r's immunity function. Phenotypic assays showed that Pf4r increased LasB activity and was also associated with a slight increase in the percentage of morphotypic variants. ChIPseq and transcriptomic analyses suggest that Pf4r also likely functions as a transcriptional regulator for other host genes. Collectively, these data suggest the mechanism by which filamentous phages play such an important role in P. aeruginosa biofilm development.
| S-EPMC8402870 | biostudies-literature
Project description:MvaT and MvaU are two redundant xenogeneic silencing proteins of the H-NS family in Pseudomonas aeruginosa. Previous studies to investigate the physiological consequences of mvaT and mvaU depletion were hampered by activation of Pf4 prophage in the resulting mutants. In this study, an mvaT mvaU double knockout mutant (PAO△TU) was constructed in a strain of PAO1 (Δpf4) devoid of the Pf4 prophage on the chromosome.Transcriptome analysis by GeneChip (Affymetrix) revealed that over 227 genes were found up-regulated in PAO△TU, including several multi-gene loci for type III and type VI protein secretion systems, O-antigen, exopolysaccharide, pili assembly, and many others of unknown functions.
2019-08-08 | GSE135506 | GEO
Project description:Hematopoietic stem cells (HSCs) responsible for blood cell production and their bone marrow regulatory niches undergo age-related changes, impacting immune responses and predisposing individuals to hematologic malignancies. Here, we show that the age-related alterations of the megakaryocytic niche and associated downregulation of Platelet Factor 4 (PF4) are pivotal mechanisms driving HSC aging. PF4-deficient mice display several phenotypes reminiscent of accelerated HSC aging, including lymphopenia, increased myeloid output, and DNA damage, mimicking physiologically aged HSCs. Remarkably, recombinant PF4 administration restored old HSCs to youthful functional phenotypes characterized by improved cell polarity, reduced DNA damage, enhanced in vivo reconstitution capacity, and balanced lineage output. Mechanistically, we identified LDLR and CXCR3 as the HSC receptors transmitting the PF4 signal, with double knockout mice showing exacerbated HSC aging phenotypes similar to PF4-deficient mice. Furthermore, human HSCs across various age groups also respond to human youthful PF4 signaling, highlighting its potential in rejuvenating aged hematopoietic systems. These findings pave the way for targeted therapies aimed at reversing age-related HSC decline with potential implications in the prevention or improvement of the course of age-related hematopoietic diseases.
2025-05-31 | GSE280042 | GEO
Project description:The tumor microenvironment (TME) contains various immune-suppressive cells such as regulatory T cells (Tregs) and M2-like tumor associated macrophages (TAMs) that express the enzyme arginase I (Arg1). T helper 1-polarized Treg (Th1-Treg) is a Treg subset that markedly accumulate in tumor tissues, suppressing anti-tumor immunity. However, little is known about the mechanism behind the abundant presence of Th1-Tregs in TME. Here we show that Arg1-expressing TAMs (Arg1+ TAMs) play critical roles for the high Th1-Treg ratio in TME. Selective depletion of Arg1+ TAMs using the VeDTR system inhibited tumor growth and concurrently reduced the Th1-Treg ratio in TME. Notably, Arg1+ TAMs secreted platelet factor 4 (PF4) that polarized Tregs to Th1-Tregs in a CXCR3-dependent manner. Both genetic PF4 inactivation and PF4 neutralization hindered Th1-Treg accumulation in TME, consequently suppressing tumor growth. Collectively, our study highlights the importance of M2-like TAM-produced PF4 for high Th1-Treg levels in TME to suppress anti-tumor immunity, and demonstrates PF4 neutralization as a potential cancer immunotherapeutic strategy by intervening the M2-like TAM/Th1-Treg axis.
2024-11-07 | GSE251735 | GEO
Project description:The tumor microenvironment (TME) contains various immune-suppressive cells such as T helper 1-polarized regulatory T cells (Th1-Tregs). However, little is known about the mechanism behind the abundant presence of Th1-Tregs in TME. In this work, we demonstrate that selective depletion of arginase I (Arg1)-expressing tumor associated macrophages (Arg1+ TAMs) inhibits tumor growth and concurrently reduces the Th1-Treg ratio in TME. Notably, Arg1+ TAMs secrete platelet factor 4 (PF4) that reinforces interferon-γ (IFN-γ)-induced Treg polarization into Th1-Tregs in a manner dependent on CXCR3 and the IFN-γ receptor. Both genetic PF4 inactivation and PF4 neutralization hinder Th1-Treg accumulation in TME, consequently suppressing tumor growth. Collectively, our study highlights the importance of Arg1+ TAM-produced PF4 for high Th1-Treg levels in TME to suppress anti-tumor immunity, and demonstrates PF4 neutralization as a potential cancer immunotherapeutic strategy.
2024-11-07 | GSE252052 | GEO
Project description:More than 20% of all Pseudomonas aeruginosa are infected with Pf4-related filamentous phage and although their role in virulence of P. aeruginosa strain PAO1 is well documented, its properties related to therapy are not elucidated in detail. The aim of this study was to determine how phage and antibiotic therapy induce Pf4, whether the released virions can infect other strains and how the phage influences the phenotype of new hosts. The subinhibitory concentrations of ciprofloxacin and mitomycin C increased Pf4 production for more than 50% during the first and sixth hour of exposure, respectively, while mutants appearing after infection with obligatory lytic phage at low MOI produced Pf4 more than four times after 12-24 h of treatment. This indicates that production of Pf4 is enhanced during therapy with these agents. The released virions can infect new P. aeruginosa strains, as confirmed for models UCBPP-PA14 (PA14) and LESB58, existing both episomally and in a form of a prophage, as confirmed by PCR, RFLP, and sequencing. The differences in properties of Pf4-infected, and uninfected PA14 and LESB58 strains were obvious, as infection with Pf4 significantly decreased cell autoaggregation, pyoverdine, and pyocyanin production, while significantly increased swimming motility and biofilm production in both strains. In addition, in strain PA14, Pf4 increased cell surface hydrophobicity and small colony variants' appearance, but also decreased twitching and swarming motility. This indicates that released Pf4 during therapy can infect new strains and cause lysogenic conversion. The infection with Pf4 increased LESB58 sensitivity to ciprofloxacin, gentamicin, ceftazidime, tetracycline, and streptomycin, and PA14 to ciprofloxacin and ceftazidime. Moreover, the Pf4-infected LESB58 was re-sensitized to ceftazidime and tetracycline, with changes from resistant to intermediate resistant and sensitive, respectively. The obtained results open a new field in phage therapy-treatment with selected filamentous phages in order to re-sensitize pathogenic bacteria to certain antibiotics. However, this approach should be considered with precautions, taking into account potential lysogenic conversion.
| S-EPMC9228429 | biostudies-literature
Project description:Platelet factors regulate wound healing and also signal from the blood to the brain. However, whether platelet factors modulate cognition, a highly valued and central manifestation of brain function, is unknown. Here, we show that systemic platelet factor 4 (PF4) modulates cognition and its molecular signature. Klotho, a longevity and cognition-enhancing protein, acutely activated platelets and increased circulating platelet factors, most robustly platelet factor 4 (PF4). To directly test PF4 effects on the brain, we treated mice with vehicle or systemic PF4. In young mice, PF4 enhanced synaptic plasticity and cognition. In aging mice, PF4 restored cognitive deficits and rejuvenated a molecular signature of cognition in the aging hippocampus. Augmenting platelet factors such as PF4, a possible messenger of klotho, may enhance cognition in the young brain and rejuvenate cognitive deficits in the aging brain.
2023-06-24 | GSE171929 | GEO