Uncultured phage
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA587536 | ENA |
REPOSITORIES: ENA
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Project description:During infection, transcriptional changes in both the phage and its host bacterium influence the outcome of infection. The xenobiotic response element (XRE) family of transcription factors (TFs), which are commonly encoded by bacteria and phages, regulate diverse aspects of bacterial cell physiology and can impact phage infection dynamics. Through a pangenome analysis of Caulobacter species isolated from soil and aquatic ecosystems, we uncovered an apparent radiation of an XRE TF gene cluster, several of which have established functions in the regulation of holdfast adhesin development and biofilm formation in C. crescentus. We further discovered related XRE TFs across the class Alphaproteobacteria and its phages, including the φCbK Caulophage, suggesting that members of this gene cluster impact host-phage interactions. Here we show that that a closely related group of XRE proteins, encoded by both C. crescentus and φCbK, can interact to form heteromeric associations and control the transcription of a common gene set, influencing processes such as adhesin development and the progression of φCbK infection. The φCbK XRE paralog, tgrL, is highly expressed at the earliest stages of infection and can directly repress transcription of hfiA, a potent adhesion factor, and gafYZ, a transcriptional activator of prophage-like gene transfer agents (GTAs) encoded on the C. crescentus chromosome. A group of C. crescentus XRE proteins also directly repress gafYZ transcription, revealing a functionally redundant set of host regulators that may protect against spurious production of GTA particles and inadvertent cell lysis. Deleting host XRE transcription factors reduced φCbK burst size, while overexpressing these genes or φCbK tgrL rescued this burst defect. We conclude that a large XRE TF gene cluster, shared by C. crescentus and φCbK, plays an important role in adhesion regulation under phage-free conditions, and influences host-phage dynamics during infection.
2023-08-25 | GSE241053 | GEO
Project description:Clinical case studies have reported that the combined use of specific lytic phage(s) and antibiotics reduces the severity of difficult-to-treat Pseudomonas aeruginosa infections in many patients. In vitro methods that attempt to reproduce specific pathophysiological conditions can provide a reliable assessment of the antibacterial effects of phages. Here, we measured bacterial killing kinetics and individual phage replication in different growth phases, including biofilms, elucidating factors influencing the efficacy of two phages against the laboratory strain P. aeruginosa PAO1. While two-phage combination treatment effectively eliminated P. aeruginosa in routine broth and in infected human lung cell cultures, the emergence of phage-resistant variants occurred under both conditions. Phage combination displayed initial inhibition of biofilm dispersal, but sustained control was achieved only with a combination of phages and meropenem. In contrast, surface-attached biofilm exhibited tolerance to phage and/or meropenem, suggesting a spatiotemporal variation in antibacterial effect. Moreover, the phage with the shorter lysis time killed P. aeruginosa more rapidly, selecting a specific nucleotide polymorphism that likely conferred a competitive disadvantage and cross resistance to the second phage of the combination. These findings highlight biofilm developmental phase, inter-phage competition and phage resistance as factors limiting the in vitro efficacy of a phage combination. However, their precise impact on the outcome of phage therapy remains uncertain, necessitating validation through phage efficacy trials in order to establish clearer correlations between laboratory assessments and clinical results.
2024-07-17 | GSE271537 | GEO
Project description:Uncultured Mediterranean Phage Metagenomics
| PRJDB1484 | ENA
Project description:Genomic material isolated from purified phage YerA41 lysate was shown to contain RNA. YerA41 phage lysate was RNase treated to remove phage-external RNA and total RNA was then isolated from the phage preparate using Qiagen Rneasy mini kit. The isolated RNA was sequenced to elucidate its origin. The results suggested that the RNA originated from intact ribosomes of the host bacterium that contaminated the phage lysate.
2022-04-04 | GSE199969 | GEO
Project description:To better understand host/phage interactions and the genetic bases of phage resistance in a model system relevant to potential phage therapy, we isolated several spontaneous mutants of the USA300 S. aureus clinical isolate NRS384 that were resistant to phage K. Six of these had a single missense mutation in the host rpoC gene, which encodes the RNA polymerase beta prime subunit. To examine the hypothesis that the mutations in the host RNA polymerase affect the transcription of phage genes, we performed RNA-seq analysis on total RNA samples collected from NRS384 wild-type (WT) and rpoC G17D mutant cultures infected with phage K, at different time points after infection. Infection of the WT host led to a steady increase of phage transcription relative to the host. Our analysis allowed us to define different early, middle, and late phage genes based on their temporal expression patterns and group them into transcriptional units. Predicted promoter sequences defined by conserved -35, -10, and in some cases extended -10 elements were found upstream of early and middle genes. However, sequences upstream of late genes did not contain clear, complete, canonical promoter sequences, suggesting that factors in addition to host RNA polymerase are required for their regulated expression. Infection of the rpoC G17D mutant host led to a transcriptional pattern that was similar to the WT at early time points. However, beginning at 20 minutes after infection, transcription of late genes (such as phage structural genes and host lysis genes) was severely reduced. Our data indicate that the rpoCG17D mutation prevents the expression of phage late genes, resulting in a failed infection cycle for phage K. In addition to illuminating the global transcriptional landscape of phage K throughout the infection cycle, these studies can inform our investigations into the bases of phage K’s control of its transcriptional program as well as mechanisms of phage resistance.
2024-10-09 | GSE253516 | GEO
Project description:During infection, transcriptional changes in both the phage and its host bacterium influence the outcome of infection. The xenobiotic response element (XRE) family of transcription factors (TFs), which are commonly encoded by bacteria and phages, regulate diverse aspects of bacterial cell physiology and can impact phage infection dynamics. Through a pangenome analysis of Caulobacter species isolated from soil and aquatic ecosystems, we uncovered an apparent radiation of an XRE TF gene cluster, several of which have established functions in the regulation of holdfast adhesin development and biofilm formation in C. crescentus. We further discovered related XRE TFs across the class Alphaproteobacteria and its phages, including the φCbK Caulophage, suggesting that members of this gene cluster impact host-phage interactions. Here we show that that a closely related group of XRE proteins, encoded by both C. crescentus and φCbK, can interact to form heteromeric associations and control the transcription of a common gene set, influencing processes such as adhesin development and the progression of φCbK infection. The φCbK XRE paralog, tgrL, is highly expressed at the earliest stages of infection and can directly repress transcription of hfiA, a potent adhesion factor, and gafYZ, a transcriptional activator of prophage-like gene transfer agents (GTAs) encoded on the C. crescentus chromosome. A group of C. crescentus XRE proteins also directly repress gafYZ transcription, revealing a functionally redundant set of host regulators that may protect against spurious production of GTA particles and inadvertent cell lysis. Deleting host XRE transcription factors reduced φCbK burst size, while overexpressing these genes or φCbK tgrL rescued this burst defect. We conclude that a large XRE TF gene cluster, shared by C. crescentus and φCbK, plays an important role in adhesion regulation under phage-free conditions, and influences host-phage dynamics during infection.
2023-08-25 | GSE241056 | GEO
Project description:hvKP ATCC43816 and its lytic phage H5 were employed as a phage-antibiotic combination model. Based on the comprehensive characterization of phages, including cryo-electron microscopy, we evaluated the synergic effect of H5 on bacterial killing in vitro when combined with multiple antibiotics, and analyzed the advantages of phage-antibiotic combinations from an evolutionary perspective and proposes a novel PAS mechanism by using ceftazidime as an example.
2023-09-14 | GSE237490 | GEO
Project description:Large-genome bacteriophages (jumbo phages) of the Chimalliviriadae family assemble a nucleus-like compartment bounded by a protein shell that protects the replicating phage genome from host-encoded restriction enzymes and CRISPR/Cas nucleases. While the nuclear shell provides broad protection against host nucleases, it necessitates transport of mRNA out of the nucleus-like compartment for translation by host ribosomes, and transport of specific proteins into the nucleus-like compartment to support DNA replication and mRNA transcription. Here we identify a conserved phage nuclear shell-associated protein that we term chimallin C (ChmC), which adopts a nucleic acid-binding fold, binds RNA with high affinity in vitro and binds phage mRNAs in infected cells. ChmC also forms phase-separated condensates with RNA. Targeted knockdown of ChmC using mRNA-targeting Cas13d halts infections at an early stage. Taken together, our data suggest that the conserved ChmC protein acts as a chaperone for phage mRNAs, potentially stabilizing these mRNAs and driving their translocation through the nuclear shell to promote translation and infection progression.
2024-03-12 | GSE243675 | GEO
Project description:Bacterial populations face the constant threat of viral predation exerted by bacteriophages (or phages). In response, bacteria have evolved a wide range of defense mechanisms against phage challenges. Here, we show that aminoglycosides, a well-known class of antibiotics produced by Streptomyces, are potent inhibitors of phage infection. We observed a broad phage inhibition by aminoglycosides. We demonstrate that aminoglycosides do not prevent the injection of phage DNA into bacterial cells but instead block an early step of the viral life cycle. In this context, we used RNA sequencing of S. venezuelae cells infected with phage Alderaan to comparatively investigate the influence of apramycin on phage DNA tanscription at two different time points after inital infection.
2021-04-30 | GSE171784 | GEO