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| Title | Structure of a bacterial Rhs effector exported by the type VI secretion system. |
|---|---|
| Journal, issue, pages | PLoS Pathog, Vol. 18, Issue 1, Page e1010182, Year 2022 |
| Publish date | Jan 5, 2022 |
 Authors | Patrick Günther / Dennis Quentin / Shehryar Ahmad / Kartik Sachar / Christos Gatsogiannis / John C Whitney / Stefan Raunser /   |
| PubMed Abstract | The type VI secretion system (T6SS) is a widespread protein export apparatus found in Gram-negative bacteria. The majority of T6SSs deliver toxic effector proteins into competitor bacteria. Yet, the ...The type VI secretion system (T6SS) is a widespread protein export apparatus found in Gram-negative bacteria. The majority of T6SSs deliver toxic effector proteins into competitor bacteria. Yet, the structure, function, and activation of many of these effectors remains poorly understood. Here, we present the structures of the T6SS effector RhsA from Pseudomonas protegens and its cognate T6SS spike protein, VgrG1, at 3.3 Å resolution. The structures reveal that the rearrangement hotspot (Rhs) repeats of RhsA assemble into a closed anticlockwise β-barrel spiral similar to that found in bacterial insecticidal Tc toxins and in metazoan teneurin proteins. We find that the C-terminal toxin domain of RhsA is autoproteolytically cleaved but remains inside the Rhs 'cocoon' where, with the exception of three ordered structural elements, most of the toxin is disordered. The N-terminal 'plug' domain is unique to T6SS Rhs proteins and resembles a champagne cork that seals the Rhs cocoon at one end while also mediating interactions with VgrG1. Interestingly, this domain is also autoproteolytically cleaved inside the cocoon but remains associated with it. We propose that mechanical force is required to remove the cleaved part of the plug, resulting in the release of the toxin domain as it is delivered into a susceptible bacterial cell by the T6SS. |
 External links | PLoS Pathog / PubMed:34986192 / PubMed Central |
| Methods | EM (single particle) |
| Resolution | 3.3 Å |
| Structure data | EMDB-13843, PDB-7q5p: EMDB-13867, PDB-7q97: |
| Source |
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 Keywords | TOXIN / bacterial type VI secretion system / VgrG / effector / Rhs repeats |
pseudomonas protegens pf-5 (bacteria)