Visualization of the Serratia Type VI Secretion System Reveals Unprovoked Attacks and Dynamic Assembly

Gerc, Amy J.; Diepold, Andreas; Trunk, Katharina; Porter, Michael; Rickman, Colin; Armitage, Judith P.; Stanley‐Wall, Nicola R.; Coulthurst, Sarah J.

doi:10.1016/j.celrep.2015.08.053

Cited by 66 publications

(105 citation statements)

References 38 publications

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“…This scenario is appealing as our study identified a predominance of T6SS1 among lesser virulent environmental strains [5]. In accordance with our hypothesis, other researchers have also suggested that the main role of the T6SS is to attack competing cells and enhance the fitness of the secreting cell in poly-microbial communities [14, 31]. However, it should be noted that although this study identified a predominance of T6SS1 among lesser virulent strains, T6SS1 was also identified in a hyper virulent environmental strain, 99–796.…”

Section: Discussionsupporting

confidence: 87%

“…The authors extrapolated this information to suggest the pivotal role played by the T6SS in affecting the composition of many poly-microbial communities and the effects of this system on health and disease outcomes [31]. Similarly, we hypothesise that the T6SS may play an important role in determining the severity of V .…”

Section: Discussionmentioning

confidence: 90%

“…In addition to environmental attacks, a recent publication demonstrated the antagonistic behavior of the T6SS in vivo [31]. The authors extrapolated this information to suggest the pivotal role played by the T6SS in affecting the composition of many poly-microbial communities and the effects of this system on health and disease outcomes [31].…”

Section: Discussionmentioning

confidence: 99%

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Vibrio vulnificus Type 6 Secretion System 1 Contains Anti-Bacterial Properties

et al. 2016

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Vibrio vulnificus is a bacterium responsible for severe gastroenteritis, sepsis and wound infections. Gastroenteritis and sepsis are commonly associated with the consumption of raw oysters, whereas wound infection is often associated with the handling of contaminated fish. Although classical virulence factors of this emerging pathogen are well characterised, there remains a paucity of knowledge regarding the general biology of this species. To investigate the presence of previously unreported virulence factors, we applied whole genome sequencing to a panel of ten V. vulnificus strains with varying virulence potentials. This identified two novel type 6 secretion systems (T6SSs), systems that are known to have a role in bacterial virulence and population dynamics. By utilising a range of molecular techniques and assays we have demonstrated the functionality of one of these T6SSs. Furthermore, we have shown that this system is subject to thermoregulation and is negatively regulated by increasing salinity concentrations. This secretion system was also shown to be involved in the killing of V. vulnificus strains that did not possess this system and a model is proposed as to how this interaction may contribute to population dynamics within V. vulnificus strains. In addition to this intra-species killing, this system also contributes to the killing of inter bacterial species and may have a role in the general composition of Vibrio species in the environment.

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Section: Discussionsupporting

confidence: 87%

Section: Discussionmentioning

confidence: 90%

Section: Discussionmentioning

confidence: 99%

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Vibrio vulnificus Type 6 Secretion System 1 Contains Anti-Bacterial Properties

et al. 2016

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“…In several organisms, T6SS sheaths were observed to assemble across the whole cell suggesting that sheath length is limited only by cell diameter. This was shown by direct observations of TssB in Vibrio cholerae , Serratia marcescens , and E. coli 181920 as well as indirectly by imaging of ClpV localization in P. aeruginosa , Burkholderia thailandensis and Bacteroidetes 21222324. The sheath contracts to about half of its initial length, presumably propelling the spike and Hcp with the associated effectors into target cells112526272829.…”

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confidence: 94%

The type VI secretion system sheath assembles at the end distal from the membrane anchor

et al. 2017

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The bacterial Type VI secretion system (T6SS) delivers proteins into target cells using fast contraction of a long sheath anchored to the cell envelope and wrapped around an inner Hcp tube associated with the secreted proteins. Mechanisms of sheath assembly and length regulation are unclear. Here we study these processes using spheroplasts formed from ampicillin-treated Vibrio cholerae. We show that spheroplasts secrete Hcp and deliver T6SS substrates into neighbouring cells. Imaging of sheath dynamics shows that the sheath length correlates with the diameter of spheroplasts and may reach up to several micrometres. Analysis of sheath assembly after partial photobleaching shows that subunits are exclusively added to the sheath at the end that is distal from the baseplate and cell envelope attachment. We suggest that this mode of assembly is likely common for all phage-like contractile nanomachines, because of the conservation of the structures and connectivity of sheath subunits.

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“…The sheath was shown to assemble across the entire width of a cell, and this allowed to use live‐cell fluorescence microscopy to study its dynamics and subcellular localization (Basler et al , 2012; Brunet et al , 2013; Gerc et al , 2015; Zoued et al , 2016; Vettiger et al , 2017). In V. cholerae , sheath assembly takes approximately 20 s (speed of assembly 30–40 nm/s) and is followed by fast contraction in less than 2 ms (speed of contraction higher than 800 μm/s) (Basler et al , 2012; Vettiger et al , 2017).…”

Section: Introductionmentioning

confidence: 99%

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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Visualization of the Serratia Type VI Secretion System Reveals Unprovoked Attacks and Dynamic Assembly

Cited by 66 publications

References 38 publications

Vibrio vulnificus Type 6 Secretion System 1 Contains Anti-Bacterial Properties

Vibrio vulnificus Type 6 Secretion System 1 Contains Anti-Bacterial Properties

The type VI secretion system sheath assembles at the end distal from the membrane anchor

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

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