Biology subjects

Faith, D. R.

Publications and source records attributed to Faith, D. R..

4 recordsLinked to original sources

bioRxiv2024

Characterization and genomic analysis of the Lyme disease spirochete bacteriophage phiBB-1

Lyme disease is a tick-borne infection caused by the spirochete Borrelia (Borreliella) burgdorferi. Borrelia species have highly fragmented genomes composed of a linear chromosome and a constellation of linear and circular plasmids some of which are required throughout the enzootic cycle. Included in this plasmid repertoire by almost all Lyme disease spirochetes are the 32-kb circular plasmid cp32 prophages that are capable of lytic replication to produce infectious virions called {phi}BB-1. While the B. burgdorferi genome contains evidence of horizontal transfer, the mechanisms of gene transfer between strains remain unclear. While we know that {phi}BB-1 transduces cp32 and shuttle vector DNA during in vitro cultivation, the extent of {phi}BB-1 DNA transfer is not clear. Herein, we use proteomics and long-read sequencing to further characterize {phi}BB-1 virions. Our studies identified the cp32 pac region and revealed that {phi}BB-1 packages linear cp32s via a headful mechanism with preferentially packaging of plasmids containing the cp32 pac region. Additionally, we find {phi}BB-1 packages fragments of the linear chromosome and full-length plasmids including lp54, cp26, and others. Furthermore, sequencing of {phi}BB-1 packaged DNA allowed us to resolve the covalently closed hairpin telomeres for the linear B. burgdorferi chromosome and most linear plasmids in strain CA-11.2A. Collectively, our results shed light on the biology of the ubiquitous {phi}BB-1 phage and further implicates {phi}BB-1 in the generalized transduction of diverse genes and the maintenance of genetic diversity in Lyme disease spirochetes.

microbiology↗

bioRxiv2023

Targeted deletion of Pf prophages from diverse Pseudomonas aeruginosa isolates impacts quorum sensing and virulence traits

Pseudomonas aeruginosa is an opportunistic bacterial pathogen that commonly causes medical hardware, wound, and respiratory infections. Temperate filamentous Pf phages that infect P. aeruginosa impact numerous bacterial virulence phenotypes. Most work on Pf phages has focused on strain Pf4 and its host P. aeruginosa PAO1. Expanding from Pf4 and PAO1, this study explores diverse Pf strains infecting P. aeruginosa clinical isolates. We describe a simple technique targeting the Pf lysogeny maintenance gene, pflM (PA0718), that enables the effective elimination of Pf prophages from diverse P. aeruginosa hosts. This study also assesses the effects different Pf phages have on host quorum sensing, biofilm formation, virulence factor production, and virulence. Collectively, this research not only introduces a valuable tool for Pf prophage elimination from diverse P. aeruginosa isolates, but also advances our understanding of the complex relationship between P. aeruginosa and filamentous Pf phages. ImportancePseudomonas aeruginosa is an opportunistic bacterial pathogen that is frequently infected by filamentous Pf phages (viruses) that integrate into its chromosome, affecting behavior. While prior work has focused on Pf4 and PAO1, this study investigates diverse Pf strains in clinical isolates. A simple method targeting the deletion of the Pf lysogeny maintenance gene pflM (PA0718) effectively eliminates Pf prophages from clinical isolates. The research evaluates the impact Pf prophages have on bacterial quorum sensing, biofilm formation, and virulence phenotypes. This work introduces a valuable tool to eliminate Pf prophages from clinical isolates and advances our understanding of P. aeruginosa and filamentous Pf phage interactions.

microbiology↗

bioRxiv2023

Inhibition of PQS signaling by the Pf bacteriophage protein PfsE enhances viral replication in Pseudomonas aeruginosa

Quorum sensing, a bacterial signaling system that coordinates group behaviors as a function of cell density, plays an important role in regulating viral (phage) defense mechanisms in bacteria. The opportunistic pathogen Pseudomonas aeruginosa is a model system for the study of quorum sensing. P. aeruginosa is also frequently infected by Pf prophages that integrate into the host chromosome. Upon induction, Pf phages suppress host quorum sensing systems; however, the physiological relevance and mechanism of suppression are unknown. Here, we identify the Pf phage protein PfsE as an inhibitor of Pseudomonas Quinolone Signal (PQS) quorum sensing. PfsE binds to the host protein PqsA, which is essential for the biosynthesis of the PQS signaling molecule. Inhibition of PqsA increases the replication efficiency of Pf virions when infecting a new host and when the Pf prophage switches from lysogenic replication to active virion replication. In addition to inhibiting PQS signaling, our prior work demonstrates that PfsE also binds to PilC and inhibits type IV pili extension, protecting P. aeruginosa from infection by type IV pili-dependent phages. Overall, this work suggests that the simultaneous inhibition of PQS signaling and type IV pili by PfsE may be a viral strategy to suppress host defenses to promote Pf replication while at the same time protecting the susceptible host from competing phages. Abbreviated summaryQuorum sensing regulates phage defense in Pseudomonas aeruginosa. The Pf phage protein PfsE inhibits PQS-mediated quorum sensing by binding to the host enzyme PqsA, while also protecting against type IV pili-dependent phage infection. This dual inhibition strategy promotes Pf replication and safeguards the host from competing phages.

microbiology↗

bioRxiv2022

Tripartite interactions between filamentous Pf4 bacteriophage, Pseudomonas aeruginosa, and bacterivorous nematodes

The opportunistic pathogen Pseudomonas aeruginosa PAO1 is infected by the filamentous bacteriophage Pf4. Pf4 virions promote biofilm formation, protect bacteria from antibiotics, and modulate animal immune responses in ways that promote infection. Furthermore, strains cured of their Pf4 infection ({Delta}Pf4) are less virulent in animal models of infection. Consistently, we find that strain {Delta}Pf4 is less virulent in a Caenorhabditis elegans nematode infection model. However, our data indicate that PQS quorum sensing is activated and production of the pigment pyocyanin, a potent virulence factor, is enhanced in strain {Delta}Pf4. The reduced virulence of {Delta}Pf4 despite high levels of pyocyanin production may be explained by our finding that C. elegans mutants unable to sense bacterial pigments through the aryl hydrocarbon receptor are more susceptible to {Delta}Pf4 infection compared to wild-type C. elegans. Collectively, our data support a model where suppression of quorum-regulated virulence factors by Pf4 allows P. aeruginosa to evade detection by innate host immune responses. Author SummaryPseudomonas aeruginosa is an opportunistic bacterial pathogen that infects wounds, lungs, and medical hardware. P. aeruginosa strains are often themselves infected by a filamentous virus (phage) called Pf. At sites of infection, filamentous Pf virions are produced that promote bacterial colonization and virulence. Here, we report that strains of P. aeruginosa cured of their Pf infection are less virulent in a Caenorhabditis elegans nematode infection model. We also report that PQS quorum sensing and production of the virulence factor pyocyanin are enhanced in P. aeruginosa strains cured of their Pf infection. Compared to wild-type C. elegans, nematodes unable to detect bacterial pigments via the aryl hydrocarbon receptor AhR were more susceptible to infection by Pf-free P. aeruginosa strains that over-produce pyocyanin. Collectively, this study supports a model where Pf phage suppress P. aeruginosa PQS quorum sensing and reduce pyocyanin production, allowing P. aeruginosa to evade AhR-mediated immune responses in C. elegans.

microbiology↗