Project description:Whole-genome sequencing is an important way to understand the genetic information, gene function, biological characteristics, and living mechanisms of organisms. There is no difficulty to have mega-level genomes sequenced at present. However, we encountered a hard-to-sequence genome of Pseudomonas aeruginosa phage PaP1. The shotgun sequencing method failed to dissect this genome. After insisting for 10 years and going over 3 generations of sequencing techniques, we successfully dissected the PaP1 genome with 91,715 bp in length. Single-molecule sequencing revealed that this genome contains lots of modified bases, including 51 N6-methyladenines (m6A) and 152 N4-methylcytosines (m4C). At the same time, further investigations revealed a novel immune mechanism of bacteria, by which the host bacteria can recognize and repel the modified bases containing inserts in large scale, and this led to the failure of the shotgun method in PaP1 genome sequencing. Strategy of resolving this problem is use of non-library dependent sequencing techniques or use of the nfi- mutant of E. coli DH5M-NM-1 as the host bacteria to construct the shotgun library. In conclusion, we unlock the mystery of phage PaP1 genome hard to be sequenced, and discover a new mechanism of bacterial immunity in present study. Methylation profiling of Pseudomonas aeruginosa phage PaP1 using kinetic data generated by single-molecule, real-time (SMRT) sequencing on the PacBio RS.
Project description:Viral genomes are most vulnerable to cellular defenses at the start of the infection. A family of jumbo phages related to phage ΦKZ, which infects Pseudomonas aeruginosa, assembles a protein-based phage nucleus to protect replicating phage DNA, but how it is protected prior to phage nucleus assembly is unclear. We find that host proteins related to membrane and lipid biology interact with injected phage protein, clustering in an early phage infection (EPI) vesicle. The injected virion RNA polymerase (vRNAP) executes early gene expression until phage genome separation from the vRNAP and the EPI vesicle, moving into the nascent proteinaceous phage nucleus. Enzymes involved in DNA replication and CRISPR/restriction immune nucleases are excluded by the EPI vesicle. We propose that the EPI vesicle is rapidly constructed with injected phage proteins, phage DNA, host lipids, and host membrane proteins to enable genome protection, early transcription, localized translation, and to ensure faithful genome transfer to the proteinaceous nucleus.
Project description:Viral genomes are most vulnerable to cellular defenses at the start of the infection. A family of jumbo phages related to phage ΦKZ, which infects Pseudomonas aeruginosa, assembles a protein-based phage nucleus to protect replicating phage DNA, but how it is protected prior to phage nucleus assembly is unclear. We find that host proteins related to membrane and lipid biology interact with injected phage protein, clustering in an early phage infection (EPI) vesicle. The injected virion RNA polymerase (vRNAP) executes early gene expression until phage genome separation from the vRNAP and the EPI vesicle, moving into the nascent proteinaceous phage nucleus. Enzymes involved in DNA replication and CRISPR/restriction immune nucleases are excluded by the EPI vesicle. We propose that the EPI vesicle is rapidly constructed with injected phage proteins, phage DNA, host lipids, and host membrane proteins to enable genome protection, early transcription, localized translation, and to ensure faithful genome transfer to the proteinaceous nucleus.
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.
Project description:Phage therapy is a promising adjunct therapeutic approach against bacterial multidrug-resistant infections, including Pseudomonas aeruginosa-derived infections. Nevertheless, the current knowledge about the phage-bacteria interaction within a human environment is limited. In this work, we performed a transcriptome analysis of phage-infected P. aeruginosa adhered to a human epithelium (Nuli-1 ATCC® CRL-4011™). To this end, we performed RNA-sequencing from a complex mixture comprising phage–bacteria–human cells at early, middle, and late infection and compared it to uninfected adhered bacteria. Overall, we demonstrated that phage genome transcription is unaltered by bacterial growth and phage employs a core strategy of predation through upregulation of prophage-associated genes, a shutdown of bacterial surface receptors, and motility inhibition. In addition, specific responses were captured under lung-simulating conditions, with the expression of genes related to spermidine syntheses, sulfate acquisition, spermidine syntheses, biofilm formation (both alginate and polysaccharide syntheses), lipopolysaccharide (LPS) modification, pyochelin expression, and downregulation of virulence regulators. These responses should be carefully studied in detail to better discern phage-induced changes from bacterial responses against phage. Our results establish the relevance of using complex settings that mimics in vivo conditions to study phage-bacteria interplay, being obvious the phage versatility on bacterial cell invasion.
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.
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 in vitro. Targeted knockdown of ChmC using mRNA-targeting dCas13d 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.
Project description:Genome-wide transcriptomics (RNA-seq) data was obtained temporally at 0, 15, 30, 45, 60 and 120 minutes of the infection with phage 18:3 on Cellulophaga baltica strain #18 to analyze, in biological triplicates, the phage and host transcriptional response during their interaction compared to the uninfected control.
Project description:The global transcriptional profile of Pseudomonas chlororaphis infecting phage 201f2-1 was obtained using the long-read RNA sequencing technique ONT-cappable-seq. this resulted in a comprehensive genome-wide map of viral transcription start and termination sites. In addition, we were able to identify different transcription units and gained new insights in the molecular mechanisms of of transcriptional regulation of members of the Phikzvirus.