Biogenesis and structure of a type VI secretion membrane core complex

Durand, Éric; Nguyen, Van Son; Zoued, Abdelrahim; Logger, Laureen; Péhau‐Arnaudet, Gérard; Aschtgen, Marie‐Stéphanie; Spinelli, S.; Desmyter, Aline; Bardiaux, Benjamin; Dujeancourt, Annick; Roussel, Alain; Cambillau, Christian; Cascales, Éric; Fronzes, Rémi

doi:10.1038/nature14667

Cited by 243 publications

(344 citation statements)

References 74 publications

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“…Conversely, it is possible that rearrangement of baseplate proteins prior to sheath contraction changes TssK conformation, and this results in opening of the connected membrane complex to allow passage of the cargo‐loaded spike and tube. Such membrane complex rearrangement was indeed proposed based on the structure of the isolated TssJLM membrane complex (Durand et al , 2015). …”

Section: Discussionmentioning

confidence: 89%

“…TssK was shown to form trimers in solution, it binds membrane complex proteins TssL/TssM as well as baseplate proteins TssF/TssG, and its spot localization correlates with T6SS activity (English et al , 2014; Brunet et al , 2015; Durand et al , 2015; Nguyen et al , 2017). Additionally, no wedge intermediate TssE–(TssF) 2 –TssG was formed in the absence of TssK (Taylor et al , 2016).…”

Section: Resultsmentioning

confidence: 99%

“…The system is composed of a long sheath surrounding an inner tube attached to a baseplate and anchored to a membrane complex that spans both membranes (Brunet et al , 2014, 2015; Durand et al , 2015). T6SS biogenesis starts by formation of the membrane complex composed of TssJLM, which recruits TssK to connect a baseplate composed of TssEFG, as well as VgrG/PAAR spike and effectors (Brunet et al , 2015; Durand et al , 2015). The baseplate then serves as a nucleation platform for polymerization of the VipA/VipB (TssB/TssC) sheath and the inner Hcp tube (Zoued et al , 2016).…”

Section: Introductionmentioning

confidence: 99%

“…The membrane complex seems to be stable at least in some organisms (Durand et al , 2015; Santin & Cascales, 2017); however, the whole T6SS was so far impossible to isolate from cells for in vitro studies. This is likely due to the highly dynamic behavior of T6SS, and it suggests that cell disruption triggers the sheath contraction, which in turn may lead to baseplate disassembly.…”

Section: Introductionmentioning

confidence: 99%

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Cryo‐ EM reconstruction of Type VI secretion system baseplate and sheath distal end

et al. 2017

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The bacterial Type VI secretion system (T6SS) assembles from three major parts: a membrane complex that spans inner and outer membranes, a baseplate, and a sheath–tube polymer. The baseplate assembles around a tip complex with associated effectors and connects to the membrane complex by TssK. The baseplate assembly initiates sheath–tube polymerization, which in some organisms requires TssA. Here, we analyzed both ends of isolated non‐contractile Vibrio cholerae sheaths by cryo‐electron microscopy. Our analysis suggests that the baseplate, solved to an average 8.0 Å resolution, is composed of six subunits of TssE/F2/G and the baseplate periphery is decorated by six TssK trimers. The VgrG/PAAR tip complex in the center of the baseplate is surrounded by a cavity, which may accommodate up to ~450 kDa of effector proteins. The distal end of the sheath, resolved to an average 7.5 Å resolution, shows sixfold symmetry; however, its protein composition is unclear. Our structures provide an important step toward an atomic model of the complete T6SS assembly.

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Section: Discussionmentioning

confidence: 89%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Cryo‐ EM reconstruction of Type VI secretion system baseplate and sheath distal end

et al. 2017

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“…Functional and structural studies have shown that the T6SS nanomachine shares striking similarities with the bacteriophage tail structure (14)(15)(16)(17)(18)(19)(20)(21)(22). Accumulating evidence suggests that the baseplate complex is recruited into the membrane-associated protein complex and initiates the polymerization of a TssB-TssC (VipAVipB) contractile sheath.…”

mentioning

confidence: 99%

VgrG C terminus confers the type VI effector transport specificity and is required for binding with PAAR and adaptor–effector complex

Bondage

Lin

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

147

273

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Type VI secretion system (T6SS) is a macromolecular machine used by many Gram-negative bacteria to inject effectors/toxins into eukaryotic hosts or prokaryotic competitors for survival and fitness. To date, our knowledge of the molecular determinants and mechanisms underlying the transport of these effectors remains limited. Here, we report that two T6SS encoded valine-glycine repeat protein G (VgrG) paralogs in Agrobacterium tumefaciens C58 specifically control the secretion and interbacterial competition activity of the type VI DNase toxins Tde1 and Tde2. Deletion and domain-swapping analysis identified that the C-terminal extension of VgrG1 specifically confers Tde1 secretion and Tde1-dependent interbacterial competition activity in planta, and the C-terminal variable region of VgrG2 governs this specificity for Tde2. Functional studies of VgrG1 and VgrG2 variants with stepwise deletion of the C terminus revealed that the C-terminal 31 aa (C31) of VgrG1 and 8 aa (C8) of VgrG2 are the molecular determinants specifically required for delivery of each cognate Tde toxin. Further in-depth studies on Tde toxin delivery mechanisms revealed that VgrG1 interacts with the adaptor/chaperone-effector complex (Tap-1-Tde1) in the absence of proline-alanine-alanine-arginine (PAAR) and the VgrG1-PAAR complex forms independent of Tap-1 and Tde1. Importantly, we identified the regions involved in these interactions. Although the entire C31 segment is required for binding with the Tap-1-Tde1 complex, only the first 15 aa of this region are necessary for PAAR binding. These results suggest that the VgrG1 C terminus interacts sequentially or simultaneously with the Tap-1-Tde1 complex and PAAR to govern Tde1 translocation across bacterial membranes and delivery into target cells for antibacterial activity.type VI secretion system | VgrG | DNase effector | interbacterial competition | Agrobacterium tumefaciens

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2020

Structure and Function of the Bacterial Genome

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Biogenesis and structure of a type VI secretion membrane core complex

Cited by 243 publications

References 74 publications

Cryo‐ EM reconstruction of Type VI secretion system baseplate and sheath distal end

Cryo‐ EM reconstruction of Type VI secretion system baseplate and sheath distal end

VgrG C terminus confers the type VI effector transport specificity and is required for binding with PAAR and adaptor–effector complex

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