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 Gramnegative 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). TamA Et was found to localize on the surface of E. tarda and be recognizable by TamA Et 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 TamA Et and TamB Et are essential for the virulence of E. tarda and required for E. tarda to survive under stress conditions.

Edwardsiella piscicida YefM-YoeB: A Type II Toxin-Antitoxin System That Is Related to Antibiotic Resistance, Biofilm Formation, Serum Survival, and Host Infection

“…In recent years, researches on the pathogenic mechanism of E. piscicida have become a research hotspot in the field of aquatic animal diseases. A variety of pathogenic factors and systems, such as adhesion factors, iron uptake regulators, antiserum ability, type III and VI secretion systems, hemolysin, catalase, cytotoxin, TAM, two-component system, density induction systems, flagellin, lysozyme inhibitors, intracellular survival mechanisms, and some environmental stress factors have been discovered and studied ( Yin et al, 2018 ; Leung et al, 2019 ; He et al, 2020 ; Li et al, 2020 ; Yoon et al, 2020 ). However, toxin-antitoxin (TA) system, an important stress and antibiotic resistance factor/system, are totally unknown in E. piscicida .…”

A Teleost CXCL10 Is Both an Immunoregulator and an Antimicrobial

“…V. anguillarum was cultured to logarithmic phase and resuspended in PBS to 1×10 6 CFU/ml. The bacteria were incubated with 4 µM rPoCXCL10 or PBS at room temperature for 4 h. After incubation, the bacteria were washed and resuspended in ultrapure water and observed with a transmission electron microscope (TEM) (Hitachi, HT7700, Japan) as described previously ( 48 ). For the PI staining assay, V. anguillarum was pretreated with rPoCXCL10 or PBS as above, and then stained with PI (2 µg/ml) for 10 min.…”

A Crustin from Hydrothermal Vent Shrimp: Antimicrobial Activity and Mechanism

“…For microscopy with TEM (HT7700, Hitachi, Tokyo, Japan), B. cereus and M. luteus were pretreated with rCrus1 or PBS as above. TEM microscopy was performed as previously reported [ 54 ]. For the PI assay, B. cereus MB1 and M. luteus were pretreated with rCrus1 or PBS as above.…”