Effector loading onto the VgrG carrier activates type VI secretion system assembly
Abstract
The type VI secretion system (T6SS) is used by many bacteria to engage in social behavior and can affect the health of its host plant or animal. Because activities associated with T6SSs are often costly, T6SSs must be tightly regulated. However, our knowledge regarding how T6SS assembly and contraction are regulated remains limited. Using the plant pathogen Agrobacterium tumefaciens, we show that effectors are not just passengers but also impact on T6SS assembly. The A. tumefaciens strain C58 encodes one T6SS and two Tde DNase toxin effectors used as major weapons for interbacterial competition. Here, we demonstrate that loading of Tde effectors onto their cognate carriers, the VgrG spikes, is required for active T6SS secretion. The assembly of the TssBC contractile sheath occurs only in the presence of Tde effectors. The requirement of effector loading for efficient T6SS secretion was also validated in other A. tumefaciens strains. We propose that such a mechanism is used by bacteria as a strategy for efficacious T6SS firing and to ensure that effectors are loaded onto the T6SS prior to completing its assembly. Show more
Permanent link
https://doi.org/10.3929/ethz-b-000385354Publication status
publishedExternal links
Journal / series
EMBO ReportsVolume
Pages / Article No.
Publisher
EMBO PressSubject
Agrobacterium tumefaciens; Effector; Interbacterial competition; Type VI secretion system; VgrGOrganisational unit
09463 - Pilhofer, Martin / Pilhofer, Martin
Funding
179255 - Structure, function, and evolution of bacterial contractile injection systems (SNF)
679209 - Multiscale model of bacterial cell-cell interactions (EC)
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