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Cell Host Microbe. 2014 Jul 9;16(1):94-104. doi: 10.1016/j.chom.2014.06.002. Epub 2014 Jun 26.

Agrobacterium tumefaciens deploys a superfamily of type VI secretion DNase effectors as weapons for interbacterial competition in planta.

Author information

1
Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan; MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, UK.
2
MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, UK.
3
Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan.
4
MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, UK. Electronic address: a.filloux@imperial.ac.uk.
5
Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan. Electronic address: emlai@gate.sinica.edu.tw.

Abstract

The type VI secretion system (T6SS) is a widespread molecular weapon deployed by many Proteobacteria to target effectors/toxins into both eukaryotic and prokaryotic cells. We report that Agrobacterium tumefaciens, a soil bacterium that triggers tumorigenesis in plants, produces a family of type VI DNase effectors (Tde) that are distinct from previously known polymorphic toxins and nucleases. Tde exhibits an antibacterial DNase activity that relies on a conserved HxxD motif and can be counteracted by a cognate immunity protein, Tdi. In vitro, A. tumefaciens T6SS could kill Escherichia coli but triggered a lethal counterattack by Pseudomonas aeruginosa upon injection of the Tde toxins. However, in an in planta coinfection assay, A. tumefaciens used Tde effectors to attack both siblings cells and P. aeruginosa to ultimately gain a competitive advantage. Such acquired T6SS-dependent fitness in vivo and conservation of Tde-Tdi couples in bacteria highlights a widespread antibacterial weapon beneficial for niche colonization.

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PMID:
24981331
PMCID:
PMC4096383
DOI:
10.1016/j.chom.2014.06.002
[Indexed for MEDLINE]
Free PMC Article

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