Project description:The phage protein gp70.1 encoded by Pseudomonas aerugonosa phage PaP3 was toxic to both P. aerugonosa and E. coli, microarry analysis was used to investigate the effects of gp70.1 on P. aerugonosa with three periods of bacterial growth.
Project description:Virulent bacteriophages (or phages) are viruses that specifically infect and lyse a bacterial host. When multiple phages co-infect a bacterial host, the extent of lysis, dynamics of bacteria-phage and phage-phage interactions are expected to vary. The objective of this study is to identify the factors influencing the interaction of two virulent phages with different Pseudomonas aeruginosa growth states (planktonic, an infected epithelial cell line, and biofilm) by measuring the bacterial time-kill and individual phage replication kinetics. A single administration of phages effectively reduced P. aeruginosa viability in planktonic conditions and infected human lung cell cultures, but phage-resistant variants subsequently emerged. In static biofilms, the phage combination displayed initial inhibition of biofilm dispersal, but sustained control was achieved only by combining phages and meropenem antibiotic. In contrast, adherent biofilms showed tolerance to phage and/or meropenem, suggesting a spatiotemporal variation in the phage-bacterial interaction. The kinetics of adsorption of each phage to P. aeruginosa during single- or co-administration were comparable. However, the phage with the shorter lysis time depleted bacterial resources early and selected a specific nucleotide polymorphism that conferred a competitive disadvantage and cross-resistance to the second phage. The extent and strength of this phage-phage competition and genetic loci conferring phage resistance, are, however, P. aeruginosa genotype dependent. Nevertheless, adding phages sequentially resulted in their unimpeded replication with no significant increase in bacterial host lysis. These results highlight the interrelatedness of phage-phage competition, phage resistance and specific bacterial growth state (planktonic/biofilm) in shaping the interplay among P. aeruginosa and virulent phages.
Project description:Pseudomonas syringae pv. phaseolicola (Pph) is a significant bacterial pathogen of agricultural crops, and phage Φ6 and other members of the dsRNA virus family Cystoviridae undergo lytic (virulent) infection of Pph, using the type IV pilus as the initial site of cellular attachment. Despite the popularity of Pph/phage Φ6 as a model system in evolutionary biology, Pph resistance to phage Φ6 remains poorly characterized. To investigate differences between phage Φ6 resistant Pseudomonas syringae pathovar phaseolicola strains, we performed expression analysis of super and non piliated strains of Pseudomonas syringae to determine the genetic cause of resistance to viral infection.
Project description:Differential RNA-seq (dRNA-seq) was performed on Pseudomonas aeruginosa alone or shortly after iinfection with the jumbo phage phiKZ
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.
Project description:Quorum sensing (QS) is the cell density-dependent virulence factor regulator in Pseudomonas aeruginosa. Here, we elucidate PIT2, a phage-encoded inhibitor of the QS regulator LasR, derived from the lytic Pseudomonas phage LMA2. PIT2 inhibits the effectors PrpL and LasA of the type 2 secretion system of P. aeruginosa and attenuates bacterial virulence towards HeLa cells and in Galleria mellonella. Using RNAseq-based differential gene expression analysis, the effect of PIT2 on the LasR regulatory network was revealed. Moreover, the specific interaction between LasR and PIT2 was determined. These data expand our knowledge on phage-encoded modulators of the bacterial metabolism, as this examples an anti-virulence protein derived from a lytic phage. From an applied perspective, this phage protein reveals and exploits an interesting anti-virulence target in P. aeruginosa. As such, it lays the foundation for a new phage-inspired anti-virulence strategy to combat multidrug resistant pathogens and opens the door for SynBio applications.
Project description:The global transcriptional profile of novel T7-like Pseudomonas aeruginosa phage LUZ100 was obtained using the long read RNA sequencing technique ONT-cappable-seq. Using this approach we obtained a comprehensive genome-wide map of viral transcription start sites, terminators and transcription units and gained new insights in the molecular mechanisms of transcriptional regulation of T7-like temperate phages.