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Envelope stress responses defend against type six secretion system attacks independently of immunity proteins.

ABSTRACT: The arms race among microorganisms is a key driver in the evolution of not only the weapons but also defence mechanisms. Many Gram-negative bacteria use the type six secretion system (T6SS) to deliver toxic effectors directly into neighbouring cells. Defence against effectors requires cognate immunity proteins. However, here we show immunity-independent protection mediated by envelope stress responses in Escherichia coli and Vibrio cholerae against a V. cholerae T6SS effector, TseH. We demonstrate that TseH is a PAAR-dependent species-specific effector highly potent against Aeromonas species but not against its V. cholerae immunity mutant or E. coli. A structural analysis reveals TseH is probably a NlpC/P60-family cysteine endopeptidase. We determine that two envelope stress-response pathways, Rcs and BaeSR, protect E. coli from TseH toxicity by mechanisms including capsule synthesis. The two-component system WigKR (VxrAB) is critical for protecting V. cholerae from its own T6SS despite expressing immunity genes. WigR also regulates T6SS expression, suggesting a dual role in attack and defence. This deepens our understanding of how bacteria survive T6SS attacks and suggests that defence against the T6SS represents a major selective pressure driving the evolution of species-specific effectors and protective mechanisms mediated by envelope stress responses and capsule synthesis.

SUBMITTER: Hersch SJ

PROVIDER: S-EPMC7190449 | biostudies-literature | 2020 May

REPOSITORIES: biostudies-literature

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Envelope stress responses defend against type six secretion system attacks independently of immunity proteins.

Hersch Steven J SJ Watanabe Nobuhiko N Stietz Maria Silvina MS Manera Kevin K Kamal Fatima F Burkinshaw Brianne B Lam Linh L Pun Alexander A Li Meixin M Savchenko Alexei A Dong Tao G TG

Nature microbiology 20200224 5

The arms race among microorganisms is a key driver in the evolution of not only the weapons but also defence mechanisms. Many Gram-negative bacteria use the type six secretion system (T6SS) to deliver toxic effectors directly into neighbouring cells. Defence against effectors requires cognate immunity proteins. However, here we show immunity-independent protection mediated by envelope stress responses in Escherichia coli and Vibrio cholerae against a V. cholerae T6SS effector, TseH. We demonstra ...[more]

PMID: 32094588

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Project description:Suspended sediments produced from dredging activities, or added to the sediment budget via river runoff, are a concern for marine resource managers. Understanding the impact of suspended sediments on critical life history stages of keystone species like corals is fundamental to effective management of coastlines and reefs. Coral embryos (Acropora tenuis and A. millepora) and larvae (A. tenuis, A. millepora and Pocillopora acuta) were subjected to a range of suspended sediment concentrations of different sediment types (siliciclastic and carbonate) to assess concentration-response relationships on ecologically relevant endpoints, including survivorship and ability to metamorphose. Embryos were subjected to short (12 h) suspended sediment exposures from ages of 3-12 hours old or a long (30 h) exposure at 6 hours old. Neither the survivorship nor metamorphosis function of embryos were significantly affected by realistic sediment exposures to ~1000 mg L-1. However, some embryos exhibited a previously undescribed response to dynamically suspended sediments, which saw 10% of the embryos form negatively buoyant cocoons at siliciclastic suspended sediment concentrations ?35 mg L-1. Scanning electron and optical microscopy confirmed the presence of a coating on these embryos, possibly mucus with incorporated sediment particles. Cocoon formation was common in embryos but not in larvae, and occurred more often after exposure to siliciclastic rather than carbonate sediments. Once transferred into sediment-free seawater, functional ~36-h-old embryos began emerging from the cocoons, coinciding with cilia development. Ciliated (> 36-h-old) larvae exposed to suspended sediments for 60 h were also observed to secrete mucus and were similarly unaffected by suspended sediment concentrations to ~800 mg L-1. This study provides evidence that mucous secretion and cilia beating effectively protect coral embryos and larvae from suspended sediment and that these mechanisms may enhance their chances of successful recruitment.

Dataset Information

Envelope stress responses defend against type six secretion system attacks independently of immunity proteins.

Publications

Envelope stress responses defend against type six secretion system attacks independently of immunity proteins.

Similar Datasets

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