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

Giuseppina Mariano, Katharina Trunk, David J. Williams, Laura Monlezun, Henrik Strahl, Samantha J. Pitt, Sarah Coulthurst (Lead / Corresponding author)

Research output: Contribution to journalArticlepeer-review

44 Citations (Scopus)
139 Downloads (Pure)


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.

Original languageEnglish
Article number5484
Pages (from-to)1-15
Number of pages15
JournalNature Communications
Issue number1
Publication statusPublished - 2 Dec 2019


  • Bacterial secretion
  • Bacterial toxins
  • Bacteriology
  • Ion channels

ASJC Scopus subject areas

  • General Chemistry
  • General Biochemistry,Genetics and Molecular Biology
  • General Physics and Astronomy


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