Abstract
The type VI secretion system (T6SS) of Gram-negative bacteria has been implicated in microbial competition; however, which components serve purely structural roles, and which serve as toxic effectors remains unresolved. Here, we present evidence that VgrG-3 of the Vibrio cholerae T6SS has both structural and toxin activity. Specifically, we demonstrate that the C-terminal extension of VgrG-3 acts to degrade peptidoglycan and hypothesize that this assists in the delivery of accessory T6SS toxins of V. cholerae. To avoid self-intoxication, V. cholerae expresses an anti-toxin encoded immediately downstream of vgrG-3 that inhibits VgrG-3-mediated lysis through direct interaction.
Highlights
The type VI secretion system provides Gram-negative bacteria with a competitive advantage
The type VI secretion system (T6SS) of Gram-negative bacteria has been implicated in microbial competition; which components serve purely structural roles, and which serve as toxic effectors remains unresolved
VgrG-3 Plays a Structural Role in the V. cholerae T6SS— Bioinformatic analysis of the full-length amino acid sequence of VgrG-3 indicated the presence of a peptidoglycan-binding motif within the C-terminal extension; unlike many characterized PG hydrolases, no catalytic domain could be identified (Fig. 1)
Summary
The type VI secretion system provides Gram-negative bacteria with a competitive advantage. Results: The V. cholerae T6SS component VgrG-3 has lysozyme-like activity that is inhibited by the product of the downstream gene tsaB. Conclusion: VgrG-3 and TsaB are a toxin-antitoxin complex of the V. cholerae T6SS. Significance: A T6SS effector is characterized along with its cognate antitoxin. The type VI secretion system (T6SS) of Gram-negative bacteria has been implicated in microbial competition; which components serve purely structural roles, and which serve as toxic effectors remains unresolved. We present evidence that VgrG-3 of the Vibrio cholerae T6SS has both structural and toxin activity. To avoid self-intoxication, V. cholerae expresses an anti-toxin encoded immediately downstream of vgrG-3 that inhibits VgrG-3-mediated lysis through direct interaction
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
