The Pseudomonas aeruginosa T6SS Delivers a Periplasmic Toxin that Disrupts Bacterial Cell Morphology
Thomas E. Wood,
Sophie A. Howard,
Andreas Förster,
Laura M. Nolan,
Eleni Manoli,
Nathan P. Bullen,
Hamish C.L. Yau,
Abderrahman Hachani,
Richard D. Hayward,
John C. Whitney,
Waldemar Vollmer,
Paul S. Freemont,
Alain Filloux
Affiliations
Thomas E. Wood
MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
Sophie A. Howard
MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
Andreas Förster
Section of Structural Biology, Department of Medicine, Imperial College London, London SW7 2AZ, UK
Laura M. Nolan
MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
Eleni Manoli
MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
Nathan P. Bullen
Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON L8S 4K1, Canada; Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4L8, Canada
Hamish C.L. Yau
Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
Abderrahman Hachani
MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
Richard D. Hayward
Division of Microbiology and Parasitology, Department of Pathology, University of Cambridge, Cambridge CB2 1QP, UK
John C. Whitney
Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON L8S 4K1, Canada; Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4L8, Canada
Waldemar Vollmer
Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
Paul S. Freemont
Section of Structural Biology, Department of Medicine, Imperial College London, London SW7 2AZ, UK
Alain Filloux
MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, UK; Corresponding author
Summary: The type VI secretion system (T6SS) is crucial in interbacterial competition and is a virulence determinant of many Gram-negative bacteria. Several T6SS effectors are covalently fused to secreted T6SS structural components such as the VgrG spike for delivery into target cells. In Pseudomonas aeruginosa, the VgrG2b effector was previously proposed to mediate bacterial internalization into eukaryotic cells. In this work, we find that the VgrG2b C-terminal domain (VgrG2bC-ter) elicits toxicity in the bacterial periplasm, counteracted by a cognate immunity protein. We resolve the structure of VgrG2bC-ter and confirm it is a member of the zinc-metallopeptidase family of enzymes. We show that this effector causes membrane blebbing at midcell, which suggests a distinct type of T6SS-mediated growth inhibition through interference with cell division, mimicking the impact of β-lactam antibiotics. Our study introduces a further effector family to the T6SS arsenal and demonstrates that VgrG2b can target both prokaryotic and eukaryotic cells. : The bacterial type VI secretion system (T6SS) delivers effector proteins into prokaryotic and eukaryotic cells to enhance the survival of the donor cell. Wood et al. describe an antibacterial T6SS toxin family eliciting a profound cell division defect and lysis. The structure of this periplasmic-acting toxin reveals a metallopeptidase fold. Keywords: type VI secretion system, VgrG, effector, metallopeptidase, Pseudomonas aeruginosa
