Type VI secretion system MIX-effectors carry both antibacterial and anti-eukaryotic activities

Ann Ray, Nika Schwartz, Marcela de Souza Santos, Junmei Zhang, Kim Orth, Dor Salomon*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Most type VI secretion systems (T6SSs) described to date are protein delivery apparatuses that mediate bactericidal activities. Several T6SSs were also reported to mediate virulence activities, although only few anti-eukaryotic effectors have been described. Here, we identify three T6SSs in the marine bacterium Vibrio proteolyticus and show that T6SS1 mediates bactericidal activities under warm marine-like conditions. Using comparative proteomics, we find nine potential T6SS1 effectors, five of which belong to the polymorphic MIX-effector class. Remarkably, in addition to six predicted bactericidal effectors, the T6SS1 secretome includes three putative anti-eukaryotic effectors. One of these is a MIX-effector containing a cytotoxic necrotizing factor 1 domain. We demonstrate that T6SS1 can use this MIX-effector to target phagocytic cells, resulting in morphological changes and actin cytoskeleton rearrangements. In conclusion, the V. proteolyticus T6SS1, a system homologous to one found in pathogenic vibrios, uses a suite of polymorphic effectors that target both bacteria and eukaryotic neighbors.

Original languageEnglish
Pages (from-to)1978-1990
Number of pages13
JournalEMBO Reports
Issue number11
StatePublished - Nov 2017


  • CNF1
  • Vibrio
  • bacterial competition
  • virulence


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