Bacteriophage-Encoded Bacterial Virulence Factors and Phage–Pathogenicity Island Interactions

Boyd, E. Fidelma

doi:10.1016/b978-0-12-394621-8.00014-5

Cited by 125 publications

(108 citation statements)

References 105 publications

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“…Phages have played significant roles in Salmonella virulence through the regulation of expression of virulence factors and the introduction of a number of effector proteins that are implicated in pathogenesis (179). A detailed understanding of the roles that bacteriophages play in Salmonella pathogenesis has been complicated by phage diversity and Salmonella strain diversity; however, it is becoming increasingly clear that phages do indeed play major roles in terms of delivering functional effector molecules and adding to the Salmonella virulence regulatory networks.…”

Section: Role Of Bacteriophages In Salmonella Evolutionmentioning

confidence: 99%

“…For example, SopE2 and SspH2 are effector proteins encoded adjacent to phagelike sequences in Salmonella. Others, such as SopE, GogB, SseI, SspH1, and SseK3, are found directly on various prophages of Salmonella (179). The distribution of these phage-encoded effector molecules is often serovar and even strain specific, suggesting that they are indeed incorporated via transducing phage (180).…”

Section: Role Of Bacteriophages In Salmonella Evolutionmentioning

confidence: 99%

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Salmonella Pathogenicity and Host Adaptation in Chicken-Associated Serovars

Foley

Johnson

Ricke

et al. 2013

Microbiol Mol Biol Rev

262

218

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SUMMARY Enteric pathogens such as Salmonella enterica cause significant morbidity and mortality. S. enterica serovars are a diverse group of pathogens that have evolved to survive in a wide range of environments and across multiple hosts. S. enterica serovars such as S . Typhi, S . Dublin, and S . Gallinarum have a restricted host range, in which they are typically associated with one or a few host species, while S . Enteritidis and S . Typhimurium have broad host ranges. This review examines how S. enterica has evolved through adaptation to different host environments, especially as related to the chicken host, and continues to be an important human pathogen. Several factors impact host range, and these include the acquisition of genes via horizontal gene transfer with plasmids, transposons, and phages, which can potentially expand host range, and the loss of genes or their function, which would reduce the range of hosts that the organism can infect. S . Gallinarum, with a limited host range, has a large number of pseudogenes in its genome compared to broader-host-range serovars. S. enterica serovars such as S . Kentucky and S . Heidelberg also often have plasmids that may help them colonize poultry more efficiently. The ability to colonize different hosts also involves interactions with the host's immune system and commensal organisms that are present. Thus, the factors that impact the ability of Salmonella to colonize a particular host species, such as chickens, are complex and multifactorial, involving the host, the pathogen, and extrinsic pressures. It is the interplay of these factors which leads to the differences in host ranges that we observe today.

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Section: Role Of Bacteriophages In Salmonella Evolutionmentioning

confidence: 99%

Section: Role Of Bacteriophages In Salmonella Evolutionmentioning

confidence: 99%

Salmonella Pathogenicity and Host Adaptation in Chicken-Associated Serovars

Foley

Johnson

Ricke

et al. 2013

Microbiol Mol Biol Rev

262

218

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“…obile integrative genetic elements (MIGEs) are the vectors of horizontal gene transfer (HGT) among bacteria via the mechanisms of transformation, transduction, and conjugation (1)(2)(3). Members of MIGEs include transposons, integrons, bacteriophages, plasmids, and integrative conjugative elements (ICEs)/ conjugative transposons and genomic/pathogenicity islands (GEIs/PAIs).…”

mentioning

confidence: 99%

“…Members of MIGEs include transposons, integrons, bacteriophages, plasmids, and integrative conjugative elements (ICEs)/ conjugative transposons and genomic/pathogenicity islands (GEIs/PAIs). Commensal bacteria can be converted into deadly pathogens through HGT of MIGEs that contain virulence factors, or a pathogen may become more virulent with the acquisition of additional virulence factors (1,(4)(5)(6). PAIs were first described for uropathogenic Escherichia coli (UPEC) and have since been described for many pathogenic bacteria (7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17).…”

mentioning

confidence: 99%

Pathogenicity Island Cross Talk Mediated by Recombination Directionality Factors Facilitates Excision from the Chromosome

2016

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Pathogenicity islands (PAIs) are mobile integrated genetic elements (MIGEs) that contain a diverse range of virulence factors and are essential in the evolution of pathogenic bacteria. PAIs are widespread among bacteria and integrate into the host genome, commonly at a tRNA locus, via integrase-mediated site-specific recombination. The excision of PAIs is the first step in the horizontal transfer of these elements and is not well understood. In this study, we examined the role of recombination directionality factors (RDFs) and their relationship with integrases in the excision of two PAIs essential for Vibrio cholerae host colonization: Vibrio pathogenicity island 1 (VPI-1) and VPI-2. VPI-1 does not contain an RDF, which allowed us to answer the question of whether RDFs are an absolute requirement for excision. We found that an RDF was required for efficient excision of VPI-2 but not VPI-1 and that RDFs can induce excision of both islands. Expression data revealed that the RDFs act as transcriptional repressors to both VPI-1-and VPI-2-encoded integrases. We demonstrated that the RDFs Vibrio excision factor A (VefA) and VefB bind at the attachment sites (overlapping the int promoter region) of VPI-1 and VPI-2, thus supporting this mode of integrase repression. In addition, V. cholerae RDFs are promiscuous due to their dual functions of promoting excision of both VPI-1 and VPI-2 and acting as negative transcriptional regulators of the integrases. This is the first demonstration of cross talk between PAIs mediated via RDFs which reveals the complex interactions that occur between separately acquired MIGEs. IMPORTANCEDeciphering the mechanisms of pathogenicity island excision is necessary for understanding the evolution and spread of these elements to their nonpathogenic counterparts. Such mechanistic insight would assist in predicting the mobility of uncharacterized genetic elements. This study identified extensive RDF-mediated cross talk between two nonhomologous VPIs and demonstrated the dual functionality of RDF proteins: (i) inducing PAI excision and (ii) acting as transcriptional regulators. Findings from this study may be implicated in determining the mobilome contribution of other bacteria with multiple MIGEs. Mobile integrative genetic elements (MIGEs) are the vectors of horizontal gene transfer (HGT) among bacteria via the mechanisms of transformation, transduction, and conjugation (1-3). Members of MIGEs include transposons, integrons, bacteriophages, plasmids, and integrative conjugative elements (ICEs)/ conjugative transposons and genomic/pathogenicity islands (GEIs/PAIs). Commensal bacteria can be converted into deadly pathogens through HGT of MIGEs that contain virulence factors, or a pathogen may become more virulent with the acquisition of additional virulence factors (1, 4-6). PAIs were first described for uropathogenic Escherichia coli (UPEC) and have since been described for many pathogenic bacteria (7-17). PAIs range in size from 10 to 200 kb and have a guanine and cytosine (GC) content ...

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“…Hosts frequently benefit from such massive gene acquisition. For example, host fitness and virulence can increase thanks to prophage genes: Numerous toxins, respiratory elements, antigenic variation systems are encoded by prophage elements (1,(4)(5)(6)(7). Therefore, the temperate phage-host relationship should be considered as beneficial or symbiotic rather than pathogenic (8).…”

mentioning

confidence: 99%

Transcription termination controls prophage maintenance in Escherichia coli genomes

Menouni

Champ

Espinosa

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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Prophages represent a large fraction of prokaryotic genomes and often provide new functions to their hosts, in particular virulence and fitness. How prokaryotic cells maintain such gene providers is central for understanding bacterial genome evolution by horizontal transfer. Prophage excision occurs through site-specific recombination mediated by a prophage-encoded integrase. In addition, a recombination directionality factor (or excisionase) directs the reaction toward excision and prevents the phage genome from being reintegrated. In this work, we describe the role of the transcription termination factor Rho in prophage maintenance through control of the synthesis of transcripts that mediate recombination directionality factor expression and, thus, excisive recombination. We show that Rho inhibition by bicyclomycin allows for the expression of prophage genes that lead to excisive recombination. Thus, besides its role in the silencing of horizontally acquired genes, Rho also maintains lysogeny of defective and functional prophages.bacteriophage | transduction | transcriptional regulation

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Bacteriophage-Encoded Bacterial Virulence Factors and Phage–Pathogenicity Island Interactions

Cited by 125 publications

References 105 publications

Salmonella Pathogenicity and Host Adaptation in Chicken-Associated Serovars

Salmonella Pathogenicity and Host Adaptation in Chicken-Associated Serovars

Pathogenicity Island Cross Talk Mediated by Recombination Directionality Factors Facilitates Excision from the Chromosome

Transcription termination controls prophage maintenance in Escherichia coli genomes

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