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International Journal of Molecular... Sep 2019TIR domain-containing proteins are essential for bacterial pathogens to subvert host defenses. This study describes a fish pathogen, SC09 strain, with a novel TIR...
TIR domain-containing proteins are essential for bacterial pathogens to subvert host defenses. This study describes a fish pathogen, SC09 strain, with a novel TIR domain-containing protein (STIR-2) that affects Toll-like receptor (TLR) function. STIR-2 was identified in by bioinformatics analysis. The toxic effects of this gene on fish were determined by in vivo challenge experiments in knockout mutants and complement mutants of the gene. In vitro, STIR-2 downregulated the expression and secretion of IL-6, IL-1β, and TNF-α. Furthermore, the results of NF-κB-dependent luciferase reporter system, co-immunoprecipitation, GST pull-down assays, and yeast two-hybrid assay indicated that STIR-2 inhibited the TLR signaling pathway by interacting with myeloid differentiation factor 88 (MyD88). In addition, STIR-2 promoted the intracellular survival of pathogenic SC09 strain by binding to the TIR adaptor protein MyD88 and inhibiting the pre-inflammatory signal of immune cells. These results showed that STIR-2 increased virulence in and suppressed the innate immune response by inhibiting TLR and MyD88-mediated signaling, serving as a novel strategy for innate immune evasion.
Topics: Adaptor Proteins, Vesicular Transport; Animals; Bacterial Adhesion; Bacterial Proteins; Fish Diseases; Fish Proteins; Gene Expression Regulation; Immune Evasion; Mice, Knockout; Myeloid Differentiation Factor 88; Oncorhynchus mykiss; Protein Domains; Signal Transduction; Toll-Like Receptors; Virulence Factors; Yersinia Infections; Yersinia ruckeri
PubMed: 31500298
DOI: 10.3390/ijms20184409 -
Marine Drugs Oct 2013Dithiolopyrrolones are a class of antibiotics that possess the unique pyrrolinonodithiole (4H-[1,2] dithiolo [4,3-b] pyrrol-5-one) skeleton linked to two variable acyl... (Review)
Review
Dithiolopyrrolones are a class of antibiotics that possess the unique pyrrolinonodithiole (4H-[1,2] dithiolo [4,3-b] pyrrol-5-one) skeleton linked to two variable acyl groups. To date, there are approximately 30 naturally occurring dithiolopyrrolone compounds, including holomycin, thiolutin, and aureothricin, and more recently thiomarinols, a unique class of hybrid marine bacterial natural products containing a dithiolopyrrolone framework linked by an amide bridge with an 8-hydroxyoctanoyl chain linked to a monic acid. Generally, dithiolopyrrolone antibiotics have broad-spectrum antibacterial activity against various microorganisms, including Gram-positive and Gram-negative bacteria, and even parasites. Holomycin appeared to be active against rifamycin-resistant bacteria and also inhibit the growth of the clinical pathogen methicillin-resistant Staphylococcus aureus N315. Its mode of action is believed to inhibit RNA synthesis although the exact mechanism has yet to be established in vitro. A recent work demonstrated that the fish pathogen Yersinia ruckeri employs an RNA methyltransferase for self-resistance during the holomycin production. Moreover, some dithiolopyrrolone derivatives have demonstrated promising antitumor activities. The biosynthetic gene clusters of holomycin have recently been identified in S. clavuligerus and characterized biochemically and genetically. The biosynthetic gene cluster of thiomarinol was also identified from the marine bacterium Pseudoalteromonas sp. SANK 73390, which was uniquely encoded by two independent pathways for pseudomonic acid and pyrrothine in a novel plasmid. The aim of this review is to give an overview about the isolations, characterizations, synthesis, biosynthesis, bioactivities and mode of action of this unique family of dithiolopyrrolone natural products, focusing on the period from 1940s until now.
Topics: Anti-Bacterial Agents; Bacteria; Biological Products; Humans; Lactams; Mupirocin; Pyrroles; Pyrrolidinones; Sulfhydryl Compounds
PubMed: 24141227
DOI: 10.3390/md11103970 -
Frontiers in Immunology 2018Outer membrane porins, as the major components of Gram-negative bacterial membrane proteins, have been proven to be involved in interactions with the host immune system...
Outer membrane porins, as the major components of Gram-negative bacterial membrane proteins, have been proven to be involved in interactions with the host immune system and potent protective antigen candidates against bacterial infection in fish. Outer membrane porin F (OmpF) is one of the major porins of (), the causative agent of enteric red mouth disease of salmonid and non-salmonid fish. In the present study, the molecular characterization and phylogenetic analysis of OmpF gene was studied, heterogenous expression, immunogenicity and protective immunity of OmpF were systemically evaluated as a subunit vaccine for channel catfish against infection. The results showed that OmpF gene was highly conserved among 15 known species based on the analysis of conserved motifs, sequences alignment and phylogenetic tree, and was subjected to negative/purifying selection with global dN/dS ratios value of 0.649 throughout the evolution. Besides, OmpF was also identified to have immunogenicity by western blotting and was verified to be located on the surface of using cell surface staining and indirect immunofluorescence assays. Moreover, recombinant OmpF (rtOmpF) as a subunit vaccine was injected with commercial adjuvant ISA763, significantly enhanced the immune response by increasing serum antibody levels, lysozyme activity, complement C3 activity, total protein content, SOD activity, immune-related genes expression in the head kidney and spleen, and survival percent of channel catfish against infection. Thus, our present results not only enriched the information of molecular characterization and phylogenetics of OmpF, but also demonstrated that OmpF holds promise to be used as a potential antigen against infection in fish.
Topics: Animals; Antibodies, Bacterial; Bacterial Vaccines; Complement C3; Fish Diseases; Fish Proteins; Head Kidney; Ictaluridae; Immunity, Innate; Molecular Structure; Phylogeny; Porins; Transcriptome; Vaccines, Subunit; Yersinia Infections; Yersinia ruckeri
PubMed: 30271401
DOI: 10.3389/fimmu.2018.02003 -
Microbiological Research Jan 2021Small noncoding RNAs (sRNAs) are important regulators of gene expression and physiology in bacteria. RyhB is an iron-responsive sRNA well characterized in Escherichia...
Small noncoding RNAs (sRNAs) are important regulators of gene expression and physiology in bacteria. RyhB is an iron-responsive sRNA well characterized in Escherichia coli and conserved in other Enterobacteriaceae. In this study, we identified and characterized two RyhB homologs (named RyhB-1 and RyhB-2) in the fish pathogen Yersinia ruckeri. We found that, as in other Enterobacteriaceae, both RyhB-1 and RyhB-2 are induced under iron starvation, repressed by the Fur regulator, and depend on Hfq for stability. Despite these similarities in expression, the mutant strains of Y. ruckeri lacking RyhB-1 (ΔryhB-1) or RyhB-2 (ΔryhB-2) exhibited differential phenotypes. In comparison with the wild type, the ΔryhB-1 strain showed a hypermotile phenotype, reduced biofilm formation, increased replication rate, faster growth, and increased ATP levels in bacterial cultures. By contrast, in salmon cell cultures, the ΔryhB-1 strain exhibited an increased survival. On the other hand, the ΔryhB-2 strain was non-motile and showed augmented biofilm formation as compared to the wild type. The expression of a subset of RyhB conserved targets, selected from different bacterial species, was analyzed by quantitative RT-PCR in wild type, ΔryhB-1, ΔryhB-2, and ΔryhB-1 ΔryhB-2 strains cultured in iron-depleted media. RyhB-1 negatively affected the expression of most analyzed genes (sodB, acnA, sdhC, bfr, fliF, among others), whose functions are related to metabolism and motility, involving iron-containing proteins. Among the genes analyzed, only sdhC and bfr appeared as targets for RyhB-2. Taken together, these results indicate that Y. ruckeri RyhB homologs participate in the modulation of the bacterial physiology with non-redundant roles.
Topics: Animals; Bacterial Physiological Phenomena; Bacterial Proteins; Biofilms; Escherichia coli; Fish Diseases; Fishes; Gene Deletion; Gene Expression Regulation, Bacterial; Homeostasis; Iron; Phenotype; RNA, Bacterial; RNA, Small Untranslated; Yersinia Infections; Yersinia ruckeri
PubMed: 33153884
DOI: 10.1016/j.micres.2020.126629 -
Journal of Proteomics May 2019Yersinia ruckeri is the aetiological agent of enteric redmouth (ERM) disease and is responsible for significant economic losses in farmed salmonids. Enteric redmouth...
Yersinia ruckeri is the aetiological agent of enteric redmouth (ERM) disease and is responsible for significant economic losses in farmed salmonids. Enteric redmouth disease is associated primarily with rainbow trout (Oncorhynchus mykiss, Walbaum) but its incidence in Atlantic salmon (Salmo salar) is increasing. Outer membrane proteins (OMPs) of Gram-negative bacteria are located at the host-pathogen interface and play important roles in virulence. The outer membrane of Y. ruckeri is poorly characterised and little is known about its composition and the roles of individual OMPs in virulence. Here, we employed a bioinformatic pipeline to first predict the OMP composition of Y. ruckeri. Comparative proteomic approaches were subsequently used to identify those proteins expressed in vitro in eight representative isolates recovered from Atlantic salmon and rainbow trout. One hundred and forty-one OMPs were predicted from four Y. ruckeri genomes and 77 of these were identified in three or more genomes and were considered as "core" proteins. Gel-free and gel-based proteomic approaches together identified 65 OMPs in a single reference isolate and subsequent gel-free analysis identified 64 OMPs in the eight Atlantic salmon and rainbow trout isolates. Together, our gel-free and gel-based proteomic analyses identified 84 unique OMPs in Y. ruckeri. SIGNIFICANCE: Yersinia ruckeri is an important pathogen of Atlantic salmon and rainbow trout and is of major economic significance to the aquaculture industry worldwide. Disease outbreaks are becoming more problematic in Atlantic salmon and there is an urgent need to investigate in further detail the cell-surface (outer membrane) composition of strains infecting each of these host species. Currently, the outer membrane of Y. ruckeri is poorly characterised and very little is known about the OMP composition of strains infecting each of these salmonid species. This study represents the most comprehensive comparative outer membrane proteomic analysis of Y. ruckeri to date, encompassing isolates of different biotypes, serotypes, OMP-types and hosts of origin and provides insights into the potential roles of these diverse proteins in host-pathogen interactions. The study has identified key OMPs likely to be involved in disease pathogenesis and makes a significant contribution to furthering our understanding of the cell-surface composition of this important fish pathogen that will be relevant to the development of improved vaccines and therapeutics.
Topics: Animals; Bacterial Outer Membrane Proteins; Computational Biology; Fish Diseases; Oncorhynchus mykiss; Proteome; Proteomics; Salmon; Virulence; Yersinia Infections; Yersinia ruckeri
PubMed: 30831250
DOI: 10.1016/j.jprot.2019.02.014 -
Journal of Fish Diseases May 2022Non-motile strains of Yersinia ruckeri, known as Y. ruckeri biotype 2, now dominate amongst clinical isolates retrieved from rainbow trout internationally. Due to an...
Non-motile strains of Yersinia ruckeri, known as Y. ruckeri biotype 2, now dominate amongst clinical isolates retrieved from rainbow trout internationally. Due to an acute increase in the number of yersiniosis cases in Norway in recent years, followed by introduction of widespread intraperitoneal vaccination against the disease, an investigation on the prevalence of Y. ruckeri biotype 2 in Norwegian aquaculture was conducted. We biotyped 263 Y. ruckeri isolates recovered from diseased salmonids in Norway between 1985 and 2020. A total of seven biotype 2 isolates were identified, four of which were collected between 1985 and 1987, and three of which belong to the current epizootic clone, isolated from two different sea-farms in 2017. Whole-genome sequencing revealed single non-synonymous nucleotide polymorphisms in the flagellar genes flhC in isolates from the 1980s, and in fliP in isolates from 2017. In both variants, motility was restored both by complementation with wild-type alleles in trans and via spontaneous mutation-driven reversion following prolonged incubation on motility agar. While biotype 2 strains do not yet seem to have become broadly established in Norwegian aquaculture, the seven isolates described here serve to document a further two independent cases of Y. ruckeri biotype 2 emergence in salmonid aquaculture.
Topics: Animals; Aquaculture; Fish Diseases; Norway; Oncorhynchus mykiss; Yersinia Infections; Yersinia ruckeri
PubMed: 35180320
DOI: 10.1111/jfd.13590 -
MicrobiologyOpen Aug 2017Despite the existence of a commercial vaccine routinely used to protect salmonids against Yersinia ruckeri, outbreaks still occur, mainly caused by nonmotile and...
Comparative genome analysis reveals important genetic differences among serotype O1 and serotype O2 strains of Y. ruckeri and provides insights into host adaptation and virulence.
Despite the existence of a commercial vaccine routinely used to protect salmonids against Yersinia ruckeri, outbreaks still occur, mainly caused by nonmotile and lipase-negative strains (serotype O1 biotype 2). Moreover, epizootics caused by other uncommon serotypes have also been reported. At the moment, one of the main concerns for the aquaculture industry is the expanding range of hosts of this pathogen and the emergence of new biotypes and serotypes causing mortality in fish farms and against which the vaccine cannot protect. The comparative analysis of the genome sequences of five Y. ruckeri strains (150, CSF007-82, ATCC29473, Big Creek 74, and SC09) isolated from different hosts and classified into different serotypes revealed important genetic differences between the genomes analyzed. Thus, a clear genetic differentiation was found between serotype O1 and O2 strains. The presence of 99 unique genes in Big Creek 74 and 261 in SC09 could explain the adaptation of these strains to salmon and catfish, respectively. Finally, the absence of 21 genes in ATCC29473 which are present in the other four virulent strains could underpin the attenuation described for this strain. The study reveals important genetic differences among the genomes analyzed. Further investigation of the genes highlighted in this study could provide insights into the understanding of the virulence and niche adaptive mechanisms of Y. ruckeri.
Topics: Adaptation, Biological; Animals; Catfishes; Genetic Variation; Genome, Bacterial; Salmon; Serogroup; Virulence; Yersinia ruckeri
PubMed: 28317294
DOI: 10.1002/mbo3.460 -
Veterinary Research Dec 2021Gram-negative bacteria are known to subvert eukaryotic cell physiological mechanisms using a wide array of virulence factors, among which the type three-secretion system... (Review)
Review
Gram-negative bacteria are known to subvert eukaryotic cell physiological mechanisms using a wide array of virulence factors, among which the type three-secretion system (T3SS) is often one of the most important. The T3SS constitutes a needle-like apparatus that the bacterium uses to inject a diverse set of effector proteins directly into the cytoplasm of the host cells where they can hamper the host cellular machinery for a variety of purposes. While the structure of the T3SS is somewhat conserved and well described, effector proteins are much more diverse and specific for each pathogen. The T3SS can remodel the cytoskeleton integrity to promote intracellular invasion, as well as silence specific eukaryotic cell signals, notably to hinder or elude the immune response and cause apoptosis. This is also the case in aquatic bacterial pathogens where the T3SS can often play a central role in the establishment of disease, although it remains understudied in several species of important fish pathogens, notably in Yersinia ruckeri. In the present review, we summarise what is known of the T3SS, with a special focus on aquatic pathogens and suggest some possible avenues for research including the potential to target the T3SS for the development of new anti-virulence drugs.
Topics: Animals; Aquatic Organisms; Bacterial Outer Membrane Proteins; Bacterial Physiological Phenomena; Fish Diseases; Fishes; Pain; Protein Transport; Type III Secretion Systems; Virulence Factors
PubMed: 34924019
DOI: 10.1186/s13567-021-01015-8 -
Journal of Applied Microbiology Mar 2017To investigate the function of the master flagellar operon flhDC in the fish pathogen Yersinia ruckeri and compare the effect of a constructed flhD mutation to a...
AIMS
To investigate the function of the master flagellar operon flhDC in the fish pathogen Yersinia ruckeri and compare the effect of a constructed flhD mutation to a naturally occurring fliR mutation causing loss-of-motility in emergent biotype 2 (BT2) strains.
METHODS AND RESULTS
Yersinia ruckeri flhD and fliR mutants were constructed in a motile strain. Both mutations caused loss-of-motility, ablation of flagellin synthesis and phospholipase secretion, similar to naturally occurring BT2 strains. Transcriptome analysis confirmed flhDC regulation of flagellar, chemotaxis and phospholipase loci as well as other genes of diverse function. The flhD mutation confers a competitive advantage within the fish host when compared with its parent strain, while this advantage was not seen with the naturally occurring fliR mutation.
CONCLUSIONS
An intact flhD is necessary for expression of the flagellar secretion system as well as other diverse loci, consistent with a role for flhD as a pleiotropic regulator. The maintenance of the flhD locus in Y. ruckeri strains suggests its importance for aspects of Y. ruckeri biology other than virulence, since the flhD mutation conferred a competitive advantage during experimental challenge of rainbow trout.
SIGNIFICANCE AND IMPACT OF THE STUDY
Yersinia ruckeri is the causative agent of enteric red mouth disease, an invasive septicaemia that affects farmed salmonid fish species. Disease outbreaks can cause severe economic losses in aquaculture. BT2 variants, which have independently emerged worldwide, are an increasing threat to farmed fish production. Knowledge of mechanisms involved in virulence, conserved functions and gene regulation among strains may be exploited for the development of novel disease control strategies to prevent pathogen growth or virulence phenotypes within aquaculture.
Topics: Animals; Aquaculture; Fish Diseases; Flagella; Gene Expression Regulation; Oncorhynchus mykiss; Operon; Transcriptome; Virulence; Yersinia Infections; Yersinia ruckeri
PubMed: 27981729
DOI: 10.1111/jam.13374 -
BMC Genomics Apr 2021Yersinia ruckeri is a pathogen that can cause enteric redmouth disease in salmonid species, damaging global production of economically important fish including rainbow...
BACKGROUND
Yersinia ruckeri is a pathogen that can cause enteric redmouth disease in salmonid species, damaging global production of economically important fish including rainbow trout (Oncorhynchus mykiss). Herein, we conducted the transcriptomic profiling of spleen samples from rainbow trout at 24 h post-Y. ruckeri infection via RNA-seq in an effort to more fully understand their immunological responses.
RESULTS
We identified 2498 differentially expressed genes (DEGs), of which 2083 and 415 were up- and down-regulated, respectively. We then conducted a more in-depth assessment of 78 DEGs associated with the immune system including CCR9, CXCL11, IL-1β, CARD9, IFN, TNF, CASP8, NF-κB, NOD1, TLR8α2, HSP90, and MAPK11, revealing these genes to be associated with 20 different immunological KEGG pathways including the Cytokine-cytokine receptor interaction, Toll-like receptor signaling, RIG-I-like receptor signaling, NOD-like receptor signaling, and MAPK signaling pathways. Additionally, the differential expression of 8 of these DEGs was validated by a qRT-PCR approach and their immunological importance was then discussed.
CONCLUSIONS
Our findings provide preliminary insight on molecular mechanism underlying the immune responses of rainbow trout following Y. ruckeri infection and the base for future studies of host-pathogen interactions in rainbow trout.
Topics: Animals; Fish Diseases; Gene Expression Profiling; Immunity; Oncorhynchus mykiss; Spleen; Yersinia Infections; Yersinia ruckeri
PubMed: 33882827
DOI: 10.1186/s12864-021-07611-4