A family of Type VI secretion system effector proteins that form ion-selective pores

Type VI secretion systems (T6SSs) are nanomachines widely used by bacteria to deliver toxic effector proteins directly into neighbouring cells. However, the modes of action of many effectors remain unknown. Here we report that Ssp6, an anti-bacterial effector delivered by a T6SS of the opportunistic pathogen Serratia marcescens, is a toxin that forms ion-selective pores. Ssp6 inhibits bacterial growth by causing depolarisation of the inner membrane in intoxicated cells, together with increased outer membrane permeability. Reconstruction of Ssp6 activity in vitro demonstrates that it forms cation-selective pores. A survey of bacterial genomes reveals that genes encoding Ssp6-like effectors are widespread in Enterobacteriaceae and often linked with T6SS genes. We conclude that Ssp6 and similar proteins represent a new family of T6SS-delivered anti-bacterial effectors.

Citation

Mariano , G , Trunk , K , Williams , D J , Monlezun , L , Strah , H , Pitt , S J & Coulthurst , S J 2019 , ' A family of Type VI secretion system effector proteins that form ion-selective pores ' , Nature Communications , vol. 10 , 5484 . https://doi.org/10.1038/s41467-019-13439-0

Publication

Nature Communications

Status

Peer reviewed

DOI

https://doi.org/10.1038/s41467-019-13439-0

ISSN

2041-1723

Type

Journal article

Rights

Copyright © The Author(s) 2019. Open Access. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visithttp://creativecommons.org/licenses/by/4.0/.

Description

This work was supported by the Wellcome Trust (104556/Z/14/Z, Senior Fellowship in Basic Biomedical Science to S.J.C.; 097818/Z/11/B and 109118/Z/15/Z, PhD studentships to University of Dundee), the MRC (MR/K000111X/1, New Investigator Research Grant to S.J.C.) and the Royal Society of Edinburgh (Biomedical Personal Research Fellowship to S.J.P.). We thank Roland Freudl for the gift of anti-OmpA antibody; Adam Ostrowski for construction of strains AO07 and AO08; Gal Horesh, Amy Dorward and Gavin Robertson for expert assistance; the Flow Cytometry and Cell Sorting Facility at the University of Dundee; and the Dundee Imaging Facility (supported by Wellcome Trust [097945/B/11/Z] and MRC [MR/K015869/1]) awards).

Collections

University of St Andrews Research

URI

http://hdl.handle.net/10023/19048