Independent Regulation of Type VI Secretion in Vibrio cholerae by TfoX and TfoY.
Type VI secretion systems (T6SSs) are nanomachines used for interbacterial killing and intoxication of eukaryotes. Although Vibrio cholerae is a model organism for structural studies on T6SSs, the underlying regulatory network is less understood. A recent study showed that the T6SS is part of the natural competence regulon in V. cholerae and is activated by the regulator TfoX. Here, we identify the TfoX homolog TfoY as a second activator of the T6SS. Importantly, despite inducing the same T6SS core machinery, the overall regulons differ significantly for TfoX and TfoY. We show that TfoY does not contribute to competence induction. Instead, TfoY drives the production of T6SS-dependent and T6SS-independent toxins, together with an increased motility phenotype. Hence, we conclude that V. cholerae uses its sole T6SS in response to diverse cues and for distinctive outcomes: either to kill for the prey's DNA, leading to horizontal gene transfer, or as part of a defensive escape reaction.
Laboratory of Molecular Microbiology, Global Health Institute, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
Lisa C
LC
Metzger
Laboratory of Molecular Microbiology, Global Health Institute, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
Sandrine
S
Stutzmann
Laboratory of Molecular Microbiology, Global Health Institute, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
Tiziana
T
Scrignari
Laboratory of Molecular Microbiology, Global Health Institute, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
Charles
C
Van der Henst
Laboratory of Molecular Microbiology, Global Health Institute, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
Noémie
N
Matthey
Laboratory of Molecular Microbiology, Global Health Institute, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland. Electronic address: melanie.blokesch@epfl.ch.
Melanie
M
Blokesch
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D058947:Bacterial Secretion Systems / Q000187:drug effects; D006152:Cyclic GMP / Q000031:analogs & derivatives / Q000494:pharmacology; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D008954:Models, Biological; D017386:Sequence Homology, Amino Acid; D014734:Vibrio cholerae / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*
D001426:Bacterial Proteins; D058947:Bacterial Secretion Systems; C062025:bis(3',5')-cyclic diguanylic acid; D006152:Cyclic GMP
TfoX-like regulators; Vibrio cholerae; interbacterial competition; motility; type VI secretion system