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The Translocation and Assembly Module (TAM) of Edwardsiella tarda Is Essential for Stress Resistance and Host Infection.

ABSTRACT: Translocation and assembly module (TAM) is a protein channel known to mediate the secretion of virulence factors during pathogen infection. Edwardsiella tarda is a Gram-negative bacterium that is pathogenic to a wide range of farmed fish and other hosts including humans. In this study, we examined the function of the two components of the TAM, TamA and TamB, of E. tarda (named tamA Et and tamB Et, respectively). TamAEt was found to localize on the surface of E. tarda and be recognizable by TamAEt antibody. Compared to the wild type, the tamA and tamB knockouts, TX01?tamA and TX01?tamB, respectively, were significantly reduced in motility, flagella formation, invasion into host cells, intracellular replication, dissemination in host tissues, and inducing host mortality. The lost virulence capacities of TX01?tamA and TX01?tamB were restored by complementation with the tamA Et and tamB Et genes, respectively. Furthermore, TX01?tamA and TX01?tamB were significantly impaired in the ability to survive under low pH and oxidizing conditions, and were unable to maintain their internal pH balance and cellular structures in acidic environments, which led to increased susceptibility to lysozyme destruction. Taken together, these results indicate that TamAEt and TamBEt are essential for the virulence of E. tarda and required for E. tarda to survive under stress conditions.

SUBMITTER: Li MF

PROVIDER: S-EPMC7393178 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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The Translocation and Assembly Module (TAM) of Edwardsiella tarda Is Essential for Stress Resistance and Host Infection.

Li Mo-Fei MF Jia Bei-Bei BB Sun Yuan-Yuan YY Sun Li L

Frontiers in microbiology 20200724

Translocation and assembly module (TAM) is a protein channel known to mediate the secretion of virulence factors during pathogen infection. Edwardsiella tarda is a Gram-negative bacterium that is pathogenic to a wide range of farmed fish and other hosts including humans. In this study, we examined the function of the two components of the TAM, TamA and TamB, of E. tarda (named tamA Et and tamB Et, respectively). TamAEt was found to loc ...[more]

PMID: 32793174

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Project description:UnlabelledEdwardsiella tarda is an important pathogenic bacterium that can replicate in macrophages. However, how the intramacrophage infection process affects the virulence of this bacterium is essentially unknown. Here, we show that E. tarda replicates and induces a caspase-1-dependent cell pyroptosis in a murine macrophage model. Via pyroptosis, intracellular E. tarda escapes to the extracellular milieu, forming a unique bacterial population. Being different from the bacteria cultured alone, this unique population possesses a reprogrammed transcriptional profile, particularly with upregulated type III secretion system (T3SS)/T6SS cluster genes. Subsequent studies revealed that the macrophage-released population gains enhanced infectivity for host epithelial cells and increases resistance to multiple host defenses and hence displays significantly promoted virulence in vivo Further studies indicated that T3SS is essentially required for the macrophage infection process, while T6SS contributes to infection-induced bacterial virulence. Altogether, this work demonstrates that E. tarda can utilize macrophages as a niche for virulence priming and for spreading infection, suggesting a positive role for intramacrophage infection in bacterial pathogenesis.ImportanceMany pathogens can replicate in macrophages, which is crucial for their pathogenesis. To survive in the macrophage cell, pathogens are likely to require fitness genes to counteract multiple host-killing mechanisms. Here, Edwardsiella tarda is proved to exit from macrophages during infection. This macrophage-released population displays a reprogrammed transcriptional profile with significantly upregulated type III secretion system (T3SS)/T6SS-related genes. Furthermore, both enhanced infectivity in epithelial cells and activated resistance to complex host defenses were conferred on this macrophage-primed population, which consequently promoted the full virulence of E. tarda in vivo Our work provides evidence that E. tarda can utilize macrophages as a niche for virulence priming and for spreading infection, highlighting the importance of the intramacrophage infection cycle for the pathogenesis of E. tarda.

Dataset Information

The Translocation and Assembly Module (TAM) of Edwardsiella tarda Is Essential for Stress Resistance and Host Infection.

Publications

The Translocation and Assembly Module (TAM) of <i>Edwardsiella tarda</i> Is Essential for Stress Resistance and Host Infection.

Similar Datasets

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