Inactivation of the T6SS inner membrane protein DotU results in severe attenuation and decreased pathogenicity of Aeromonas veronii TH0426

Abstract

Background: The inner membrane protein DotU of Aeromonas veronii is an important component of the minimal core conserved membrane proteome required for the formation of an envelope-transmembrane complex. This protein functions in a type VI secretion system (T6SS), and the role of this T6SS during the pathogenic process has not been clearly described. Results: A recombinant A. veronii with a partial disruption of the dotU gene (720 bp of the in-frame sequence) (defined as ΔdotU) was constructed by two conjugate exchanges. We found that the mutant ΔdotU allele can be stably inherited for more than 50 generations. Inactivation of the A. veronii dotU gene resulted in no significant changes in growth or resistance to various environmental changes. However, compared with the wild-type strain colony, the mutant ΔdotU colony had a rough surface morphology. In addition, the biofilm formation ability of the mutant ΔdotU was significantly enhanced by 2.1-fold. Conversely, the deletion of the dotU gene resulted in a significant decrease in pathogenicity and infectivity compared to those of the A. veronii wild-type strain. Conclusions: Our findings indicated that the dotU gene was an essential participant in the pathogenicity and invasiveness of A. veronii TH0426, which provides a novel perspective on the pathogenesis of TH0426 and lays the foundation for discovering potential T6SS effectors.

The role of dctP gene in regulating colonization, adhesion and pathogenicity of Vibrio alginolyticus strain HY9901

“…DotU as one of inner membrane protein components of joining complex of the T6SS, the deletion of dotU in Aeromonas veronii has shown the decrease by 50.4-fold virulence for adult zebrafish (Song et al, 2020). In our study, the activity of ECPase decreased and 50% lethal dose increased in ΔdctP compared to those in WT.…”

“…KatA, as a major catalase, is required for hydrogen peroxide (H 2 O 2 ) resistance and has a significant impact on virulence change of Pseudomonas aeruginosa (Kim et al., 2019). T6SS, as a shrinkable nanomachine, can transport and inject toxins to other bacteria and host eukaryotic cells (Song et al., 2020). ClpV plays the important role in the T6SS reassembly and T6SS effectors secretion and also has been confirmed to be a key virulence factor of Pseudomonas plecoglossicida (Luo et al., 2019).…”

“…ClpV plays the important role in the T6SS reassembly and T6SS effectors secretion and also has been confirmed to be a key virulence factor of Pseudomonas plecoglossicida (Luo et al., 2019). DotU as one of inner membrane protein components of joining complex of the T6SS, the deletion of dotU in Aeromonas veronii has shown the decrease by 50.4‐fold virulence for adult zebrafish (Song et al., 2020). In our study, the activity of ECPase decreased and 50% lethal dose increased in Δ dctP compared to those in WT.…”

Aeromonas veronii virulence and adhesion attenuation mediated by the gene aodp

“…According to the previously modified method, 10 μl of each bacterial suspension was inoculated onto the sheep blood plate (Song et al., 2020). After the bacterial suspension was completely absorbed, the plate was cultured in a 28°C incubator for 24 h to observe the haemolytic activity of A. veronii TH0426, △‐ aodp and C‐ aodp strains.…”

“…The effect of △‐ aodp and C‐ aodp strains on the adhesion process of EPCs was determined based on the previously proposed method with slight modifications (Song et al., 2020). Briefly, EPCs were cultured, adjusted to 1 × 10 5 cell/well and inoculated into a 24‐well cell plate for 12 h. The monolayer cells were washed twice with M199 medium (without antibiotics and serum).…”