Definition of a Bacterial Type IV Secretion Pathway for a DNA Substrate

Cascales, Éric; Christie, Peter J.

doi:10.1126/science.1095211

Cited by 328 publications

(504 citation statements)

References 26 publications

(31 reference statements)

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“…Coupling proteins in conjugative T4SSs play important roles in recruiting the substrate to the T4S machinery (Cabezon et al , 1997; Cascales & Christie, 2004; Lang et al , 2010, 2011). Although a lot of information has been gathered over the years about the activity, oligomerization state and structure as well as the importance of VirD4 with respect to substrate recognition and processing, its location within the T4S system was unknown (Cascales & Christie, 2004; Mihajlovic et al , 2009; Lang et al , 2010; de Paz et al , 2010; Whitaker et al , 2016).…”

Section: Resultsmentioning

confidence: 99%

“…Although a lot of information has been gathered over the years about the activity, oligomerization state and structure as well as the importance of VirD4 with respect to substrate recognition and processing, its location within the T4S system was unknown (Cascales & Christie, 2004; Mihajlovic et al , 2009; Lang et al , 2010; de Paz et al , 2010; Whitaker et al , 2016). This is the issue we set out to address in this study.…”

Section: Resultsmentioning

confidence: 99%

“…While VirB4 together with VirB11 are required for pilus biogenesis and substrate translocation, VirD4 plays the role of a coupling protein, responsible for the recruitment of the substrate to the T4S system channel (Cabezon et al , 1997, 2015; Cascales & Christie, 2004). VirB11 has been reported as a hexamer in different systems (Machon et al , 2002; Savvides et al , 2003; Hare et al , 2006).…”

Section: Introductionmentioning

confidence: 99%

“…Most of the knowledge about the path of the secreted DNA comes from the A. tumefaciens system where the proteins with which the DNA interacts on its way through the secretion channel have been identified. During transfer, a single strand of DNA makes successive contact with the VirD4 coupling protein, and then the VirB11 ATPase, the inner membrane proteins VirB6 and VirB8 and finally the core complex proteins VirB7 and VirB9 (Cascales & Christie, 2004). …”

Section: Introductionmentioning

confidence: 99%

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Structure of a VirD4 coupling protein bound to a VirB type IV secretion machinery

et al. 2017

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Type IV secretion (T4S) systems are versatile bacterial secretion systems mediating transport of protein and/or DNA. T4S systems are generally composed of 11 VirB proteins and 1 VirD protein (VirD4). The VirB1‐11 proteins assemble to form a secretion machinery and a pilus while the VirD4 protein is responsible for substrate recruitment. The structure of VirD4 in isolation is known; however, its structure bound to the VirB1‐11 apparatus has not been determined. Here, we purify a T4S system with VirD4 bound, define the biochemical requirements for complex formation and describe the protein–protein interaction network in which VirD4 is involved. We also solve the structure of this complex by negative stain electron microscopy, demonstrating that two copies of VirD4 dimers locate on both sides of the apparatus, in between the VirB4 ATPases. Given the central role of VirD4 in type IV secretion, our study provides mechanistic insights on a process that mediates the dangerous spread of antibiotic resistance genes among bacterial populations.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Structure of a VirD4 coupling protein bound to a VirB type IV secretion machinery

et al. 2017

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“…VirB6 is a polytopic inner-membrane protein that forms part of the lumen of the Mpf channel structure, as detected by TrIP analysis in A. tumefaciens (Cascales and Christie, 2004b;Jakubowski et al, 2004). Together with VirB8, VirB6 is required for delivery of the T-DNA substrate to the outermembrane-associated components VirB2 and VirB9 (Cascales and Christie, 2004b).…”

Section: Virb6: a Modulator Of The Secretion Channel?mentioning

confidence: 99%

The mating pair formation system of conjugative plasmids—A versatile secretion machinery for transfer of proteins and DNA

Schröder

Lanka

2005

Plasmid

190

146

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The mating pair formation (Mpf) system functions as a secretion machinery for intercellular DNA transfer during bacterial conjugation. The components of the Mpf system, comprising a minimal set of 10 conserved proteins, form a membrane-spanning protein complex and a surface-exposed sex pilus, which both serve to establish intimate physical contacts with a recipient bacterium. To function as a DNA secretion apparatus the Mpf complex additionally requires the coupling protein (CP). The CP interacts with the DNA substrate and couples it to the secretion pore formed by the Mpf system. Mpf/CP conjugation systems belong to the family of type IV secretion systems (T4SS), which also includes DNA-uptake and -release systems, as well as eVector protein translocation systems of bacterial pathogens such as Agrobacterium tumefaciens (VirB/VirD4) and Helicobacter pylori (Cag). The increased eVorts to unravel the molecular mechanisms of type IV secretion have largely advanced our current understanding of the Mpf/CP system of bacterial conjugation systems. It has become apparent that proteins coupled to DNA rather than DNA itself are the actively transported substrates during bacterial conjugation. We here present a uniWed and updated view of the functioning and the molecular architecture of the Mpf/CP machinery. 

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The type IV secretion system core component VirB8 interacts via the β1‐strand with VirB10

et al. 2017

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In this work, we provide evidence for the interactions between VirB8 and VirB10, two core components of the type IV secretion system (T4SS). Using nuclear magnetic resonance experiments, we identified residues on the β1-strand of Brucella VirB8 that undergo chemical shift changes in the presence of VirB10. Bacterial two-hybrid experiments confirm the importance of the β1-strand, whereas phage display experiments suggest that the α2-helix of VirB8 may also contribute to the interaction with VirB10. Conjugation assays using the VirB8 homolog TraE as a model show that several residues on the β1-strand of TraE are important for T4SS function. Together, our results suggest that the β1-strand of VirB8-like proteins is essential for their interaction with VirB10 in the T4SS complex.

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Definition of a Bacterial Type IV Secretion Pathway for a DNA Substrate

Cited by 328 publications

References 26 publications

Structure of a VirD4 coupling protein bound to a VirB type IV secretion machinery

Structure of a VirD4 coupling protein bound to a VirB type IV secretion machinery

The mating pair formation system of conjugative plasmids—A versatile secretion machinery for transfer of proteins and DNA

The type IV secretion system core component VirB8 interacts via the β1‐strand with VirB10

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