Bacterial type VI secretion system facilitates niche domination

Dörr, Natália C. Drebes; Blokesch, Melanie

doi:10.1073/pnas.1812776115

Cited by 18 publications

(19 citation statements)

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“…Metabolism of the sugars galactose and mannose are also critical to surviving in these environments so they can take advantage of these nutrients. Lastly, T6SS-associated proteins are widely distributed in gram-negative bacteria and this secretion system is used as a molecular weapon against hosts, predators and competitors [53]. In Cronobacter , T6SS likely plays a role in cellular invasion, adherence, cytotoxicity, and growth inside macrophages [38].…”

Section: Resultsmentioning

confidence: 99%

Pan-genome diversification and recombination in Cronobacter sakazakii, an opportunistic pathogen in neonates, and insights to its xerotolerant lifestyle

Lee

Andam

2019

BMC Microbiol

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BackgroundCronobacter sakazakii is an emerging opportunistic bacterial pathogen known to cause neonatal and pediatric infections, including meningitis, necrotizing enterocolitis, and bacteremia. Multiple disease outbreaks of C. sakazakii have been documented in the past few decades, yet little is known of its genomic diversity, adaptation, and evolution. Here, we analyzed the pan-genome characteristics and phylogenetic relationships of 237 genomes of C. sakazakii and 48 genomes of related Cronobacter species isolated from diverse sources.ResultsThe C. sakazakii pan-genome contains 17,158 orthologous gene clusters, and approximately 19.5% of these constitute the core genome. Phylogenetic analyses reveal the presence of at least ten deep branching monophyletic lineages indicative of ancestral diversification. We detected enrichment of functions involved in proton transport and rotational mechanism in accessory genes exclusively found in human-derived strains. In environment-exclusive accessory genes, we detected enrichment for those involved in tryptophan biosynthesis and indole metabolism. However, we did not find significantly enriched gene functions for those genes exclusively found in food strains. The most frequently detected virulence genes are those that encode proteins associated with chemotaxis, enterobactin synthesis, ferrienterobactin transporter, type VI secretion system, galactose metabolism, and mannose metabolism. The genes fos which encodes resistance against fosfomycin, a broad-spectrum cell wall synthesis inhibitor, and mdf(A) which encodes a multidrug efflux transporter were found in nearly all genomes. We found that a total of 2991 genes in the pan-genome have had a history of recombination. Many of the most frequently recombined genes are associated with nutrient acquisition, metabolism and toxin production.ConclusionsOverall, our results indicate that the presence of a large accessory gene pool, ability to switch between ecological niches, a diverse suite of antibiotic resistance, virulence and niche-specific genes, and frequent recombination partly explain the remarkable adaptability of C. sakazakii within and outside the human host. These findings provide critical insights that can help define the development of effective disease surveillance and control strategies for Cronobacter-related diseases.

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Section: Resultsmentioning

confidence: 99%

Pan-genome diversification and recombination in Cronobacter sakazakii, an opportunistic pathogen in neonates, and insights to its xerotolerant lifestyle

Lee

Andam

2019

BMC Microbiol

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“…Commensurate with these advantages, there is growing evidence of the important role the T6SS plays in microbial ecosystems. The T6SS can be a powerful mediator of interbacterial competition across a broad range of contexts, including plant-and human-associated communities [3,[11][12][13]. In these settings, it facilitates pathogen invasion through the killing of commensal species-but, conversely, it can allow commensals to defend ecological niches from competitors and pathogens [14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

The evolution of the type VI secretion system as a disintegration weapon

et al. 2020

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The type VI secretion system (T6SS) is a nanomachine used by many bacteria to drive a toxin-laden needle into other bacterial cells. Although the potential to influence bacterial competition is clear, the fitness impacts of wielding a T6SS are not well understood. Here we present a new agent-based model that enables detailed study of the evolutionary costs and benefits of T6SS weaponry during competition with other bacteria. Our model identifies a key problem with the T6SS. Because of its short range, T6SS activity becomes self-limiting, as dead cells accumulate in its way, forming "corpse barriers" that block further attacks. However, further exploration with the model presented a solution to this problem: if injected toxins can quickly lyse target cells in addition to killing them, the T6SS becomes a much more effective weapon. We tested this prediction with single-cell analysis of combat between T6SS-wielding Acinetobacter baylyi and T6SS-sensitive Escherichia coli. As predicted, delivery of lytic toxins is highly effective, whereas nonlytic toxins leave large patches of E. coli alive. We then analyzed hundreds of bacterial species using published genomic data, which suggest that the great majority of T6SS-wielding species do indeed use lytic toxins, indicative of a general principle underlying weapon evolution. Our work suggests that, in the T6SS, bacteria have evolved a disintegration weapon whose effectiveness often rests upon the ability to break up competitors. Understanding the evolutionary function of bacterial weapons can help in the design of probiotics that can both establish well and eliminate problem species.

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“…The extended contractile sheath is broken down and the components recycled by the TssH ATPase for further sheath assembly (Kapitein et al, 2013). Delivery of effector proteins by the T6SS to target cells can exert a number of effects including colonization and niche establishment (Kapitein and Mogk, 2014;Ma et al, 2014;Drebes Dorr and Blokesch, 2018). T6SS effectors can target and eliminate bacterial and fungal competitors and also affect eukaryotic host cells (Murdoch et al, 2011;Trunk et al, 2018).…”

Section: Introductionmentioning

confidence: 99%