7Q97

Structure of the bacterial type VI secretion system effector RhsA.

Summary for 7Q97

• Entry DOI: 10.2210/pdb7q97/pdb
• EMDB information: 13867
• Descriptor: Rhs family protein (1 entity in total)
• Functional Keywords: bacterial type vi secretion system, effector, rhs repeats, toxin
• Biological source: Pseudomonas protegens Pf-5
• Total number of polymer chains: 2
• Total formula weight: 319438.91

Authors

Guenther, P.,Quentin, D.,Ahmad, S.,Sachar, K.,Gatsogiannis, C.,Whitney, J.C.,Raunser, S. (deposition date: 2021-11-12, release date: 2021-12-22, Last modification date: 2024-07-17)

Primary citation

Gunther, P.,Quentin, D.,Ahmad, S.,Sachar, K.,Gatsogiannis, C.,Whitney, J.C.,Raunser, S.
Structure of a bacterial Rhs effector exported by the type VI secretion system.
Plos Pathog., 18:e1010182-e1010182, 2022

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 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.

PubMed: 34986192
DOI: 10.1371/journal.ppat.1010182

Experimental method

ELECTRON MICROSCOPY (3.3 Å)