Instruct: Identify the main category of Biorxiv papers based on the titles and abstracts
Query: Structure of a bacterial Rhs effector exported by the type VI secretion system 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 [A] resolution. The structures reveal that the rearrangement hotspot (Rhs) repeats of RhsA assemble into a closed anticlockwise {beta}-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.
1
The categories of this paper are: bioinformatics
4
The categories of this paper are: neuroscience
13
The categories of this paper are: animal
9
The categories of this paper are: synthetic
32
The categories of this paper are: zoology
22
The categories of this paper are: physiology
17
The categories of this paper are: molecular
15
The categories of this paper are: developmental
21
The categories of this paper are: toxicology
20
The categories of this paper are: pharmacology
5
The categories of this paper are: cell
7
The categories of this paper are: ecology
23
The categories of this paper are: immunology
11
The categories of this paper are: cognition
30
The categories of this paper are: scientific
14
The categories of this paper are: biophysics