In sílico identification and characterization of putative Dot/Icm secreted virulence effectors in the fish pathogen Piscirickettsia salmonis

Labra, Álvaro; Arredondo-Zelada, Oscar; Flores-Herrera, Patricio; Marshall, Sergio H.; Gómez, Fernando

doi:10.1016/j.micpath.2015.12.002

Cited by 13 publications

(10 citation statements)

References 56 publications

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“…Using bioinformatics approaches, 18 putative Dot/Icm substrates were predicted for R. grylli , of which six were homologs of effectors in L. pneumophila strain Philadelphia (Lifshitz et al 2013). In Piscirickettsia , four effectors have been identified through genetic screening (Labra et al 2016) that exhibit clear matches with effectors in either L. pneumophila or C. burnetii . These effectors all have eukaryotic-like protein domains, revealing a possible common function upon translocation to the eukaryotic host during the establishment of pathogen–host relationships.…”

Section: Comparisons Of Effectors Secreted Through Different Dot/imentioning

confidence: 99%

Biological Diversity and Evolution of Type IV Secretion Systems

Christie¹,

Gómez-Valero

Buchrieser

2017

Current Topics in Microbiology and Immunology

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The bacterial type IV secretion systems (T4SSs) are a highly functionally and structurally diverse superfamily of secretion systems found in many species of gram-negative and -positive bacteria. Collectively, the T4SSs can translocate DNA and monomeric and multimeric protein substrates to a variety of bacterial and eukaryotic cell types. Detailed phylogenomics analyses have established that the T4SSs evolved from ancient conjugation machines whose original functions were to disseminate mobile DNA elements within and between bacterial species. How members of the T4SS superfamily evolved to recognize and translocate specific substrate repertoires to prokaryotic or eukaryotic target cells is a fascinating question from evolutionary, biological, and structural perspectives. In this chapter, we will summarize recent findings that have shaped our current view of the biological diversity of the T4SSs. We focus mainly on two subtypes, designated as the types IVA (T4ASS) and IVB (T4BSS) systems that respectively are represented by the paradigmatic Agrobacterium tumefaciens VirB/VirD4 and Legionella pneumophila Dot/Icm T4SSs. We present current information about the composition and architectures of these representative systems. We also describe how these and a few related T4ASS and T4BSS members evolved as specialized nanomachines through acquisition of novel domains or subunits, a process that ultimately generated extensive genetic and structural mosaicism among this secretion superfamily. Finally, we present new phylogenomics information establishing that the T4BSSs are much more broadly distributed than initially envisioned.

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Section: Comparisons Of Effectors Secreted Through Different Dot/imentioning

confidence: 99%

Biological Diversity and Evolution of Type IV Secretion Systems

Christie¹,

Gómez-Valero

Buchrieser

2017

Current Topics in Microbiology and Immunology

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“…It was recently reported that P . salmonis can inhibit phagosome-lysosome fusion by secreting virulence effectors via the Dot/Icm secretion system [ 10 , 11 ]. Therefore, while it is clear that this mechanism is among the strategies employed by P .…”

Section: Introductionmentioning

confidence: 99%

Piscirickettsia salmonis Imbalances the Innate Immune Response to Succeed in a Productive Infection in a Salmonid Cell Line Model

et al. 2016

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Piscirickettsia salmonis is a facultative intracellular bacterium that causes the disease called “salmon rickettsial syndrome”. Attempts to control this disease have been unsuccessful, because existing vaccines have not achieved the expected effectiveness and the antibiotics used fail to completely eradicate the pathogen. This is in part the product of lack of scientific information that still lacks on the mechanisms used by this bacterium to overcome infected–cell responses and survive to induce a productive infection in macrophages. For that, this work was focused in determining if P. salmonis is able to modify the expression and the imbalance of IL-12 and IL-10 using an in vitro model. Additionally, we also evaluated the role the antimicrobial peptide hepcidin had in the control of this pathogen in infected cells. Therefore, the expression of IL-10 and IL-12 was evaluated at earlier stages of infection in the RTS11 cell line derived from Oncorhynchus mykiss macrophages. Simultaneously, the hepcidin expression and location was analyzed in the macrophages infected with the pathogen. Our results suggest that IL-10 is clearly induced at early stages of infection with values peaking at 36 hours post infection. Furthermore, infective P. salmonis downregulates the expression of antimicrobial peptide hepcidin and vesicles containing this peptide were unable to merge with the infective bacteria. Our results suggest that P. salmonis is able to manipulate the behavior of host cytokines and likely might constitute a virulence mechanism that promotes intracellular bacterial replication in leukocytes cells lines of trout and salmon. This mechanism involves the generation of an optimum environment for the microorganism and the downregulation of antimicrobial effectors like hepcidin.

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“…This constitutes robust evidence of the importance of both genes during infection. As acidic pH is known to trigger expression of the dot/icm secretion system, the known primary virulence mechanism in P. salmonis (Bohle et al., ; Gómez et al., ; Labra et al., ), each hfq was evaluated at acidic pHs. A slight increase in hfq‐1 expression was seen at pH 4.5 in comparison with pH 5.5 and 6.5 (Figure a); however, hfq‐2 significantly overexpressed only at pH 4.5, with an exponential increase 72 hr post‐infection.…”

Section: Discussionmentioning

confidence: 99%

“…Although the complete genome sequences of different P. salmonis isolates were recently reported (Bohle et al., ; Eppinger et al., ; Pulgar et al., ; Yañez et al., ), relevant aspects, such as metabolism, virulence and life cycle, remain poorly understood. One of the most important virulence mechanism described for P. salmonis is the Dot/Icm secretion system (Defect in Organelle Trafficking/Intracellular Multiplication), including at least four associated virulence effectors, which could be responsible for bacterial intracellular survival and pathogenic potential (Gómez et al., ; Labra, Arredondo‐Zelada, Flores‐Herrera, Marshall, & Gómez, ). However, the exact virulence components and its regulation remain unknown.…”

Section: Introductionmentioning

confidence: 99%

Identification and characterization of two variants of the Hfq‐sRNA‐chaperone in the fish pathogen Piscirickettsia salmonis

Marshall

Flores-Herrera

Henríquez

et al. 2017

Journal of Fish Diseases

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Small RNA and chaperone proteins form synergistic duos that play pivotal roles in controlling gene expression in bacteria. This is the case for Hfq, a highly pleiotropic pretranslational modulator of general protein expression, which responds to harsh environmental conditions and influences fitness and virulence in a wide range of pathogenic Enterobacteria. Given this relevancy, we evaluated the presence and potential role of Hfq in the fish pathogen Piscirickettsia salmonis, a Gram-negative bacterium that threatens the sustainability of Chilean salmon production. Using bioinformatics tools were identified and characterized two variants of Hfq, which share the consensus RNA-binding domains and the active sites described functional Hfq other bacteria. Additionally, we demonstrated that hfq-1 and hfq-2 were transcriptionally active when growing in cell-free media and in infected susceptible fish cell line. Expression of both genes differed under different growth conditions and under stress, suggesting that their roles might be independent and different, depending on the bacterial physiological status. In conclusion, we demonstrate the existence of two different and functional ORF coding for the hfq marker in marine bacteria and a preliminary analysis indicating that these two novel proteins might have relevant roles in the biology and pathogenic potential of P. salmonis.

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In sílico identification and characterization of putative Dot/Icm secreted virulence effectors in the fish pathogen Piscirickettsia salmonis

Cited by 13 publications

References 56 publications

Biological Diversity and Evolution of Type IV Secretion Systems

Biological Diversity and Evolution of Type IV Secretion Systems

Piscirickettsia salmonis Imbalances the Innate Immune Response to Succeed in a Productive Infection in a Salmonid Cell Line Model

Identification and characterization of two variants of the Hfq‐sRNA‐chaperone in the fish pathogen Piscirickettsia salmonis

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