Surprisingly, we discovered that each Ralstonia wilt pathogen required multiple #T6SS antitoxin/immunity genes.

Most immunity mutants had no fitness defect in ex vivo
xylem sap or rich broth or minimal medium broth.

2/2
In this Brief Communication, we also show that although some anti-eukaryotic #T6SS effectors are toxic during infection of immune cells from different hosts, others are only toxic to some hosts.
A fun collaboration with the Gerlic lab and the Bar Yaacov lab.
#Vibrio 🦠

1/2
"All T6SS-inducing regulators are equal, but some regulators are more equal than others".
Preprint 🚨: We use #Vibrio to show that #T6SS activation by regulator manipulation may result in the expression of different effector repertoires, affecting toxicity 🦠
www.biorxiv.org/content/10.6...

Aeromonas adhesins facilitate kin and non-kin attachment to enable T6SS-mediated antagonism in liquid Bacterial ability to deploy the type VI secretion system (T6SS) against rivals requires prolonged cell-cell interactions. Such interactions are facilitated on solid surfaces but are assumed to be absent in liquid, leading to the conventional dismissal of T6SS-mediated competition in liquid environments. Here, we find that Aeromonas jandaei employs its T6SS to eliminate diverse bacterial competitors in liquid media. Using a workflow that monitors interbacterial competition via prey luminescence, we demonstrate that auto-aggregation and co-aggregation, facilitated by distinct adhesins, enable kin and non-kin recognition and intoxication in a T6SS-dependent manner. Furthermore, we show that another marine bacterium, Vibrio coralliilyticus , employs T6SS to intoxicate rivals in liquid media. Collectively, our results indicate that T6SS-mediated competition in liquid is more common in marine bacteria than previously anticipated, and can be facilitated by diverse molecular mechanisms that govern cell aggregation. ### Competing Interest Statement The authors have declared no competing interest. Israel Science Foundation, https://ror.org/04sazxf24, 1362/21, 2174/22 Swiss National Science Foundation, 51NF40_180541

It is widely accepted that #T6SS -mediated intoxication occurs only on solid surfaces, where prolonged cell-cell interactions are forced, and not in liquid environments. But is this generalization true? Our new preprint says it isn't. A 🧵 ...
biorxiv.org/content/10.6...
🦠

TseVF-TsiVF, a novel bacteriolytic effector-immunity pair of #Vibrio fluvialis VflT6SS2, provides a fitness advantage in microbial competition

www.sciencedirect.com/science/arti... #OpenAccess #T6SS #MicroSky

Mechanisms of Pseudomonas aeruginosa resistance to type VI secretion system attacks Nature Communications - Pseudomonas aeruginosa H1-T6SS delivers effectors in response to exogenous T6SS attacks. In this study, a CRISPRi screen identifies pathways involved in P. aeruginosa...

Big congrats to @atejadaarranz.bsky.social and co-authors on this paper showing novel insights into the resistance to #T6SS effectors and an unexpected link to antibiotic resistance!

Thanks @nccr-antiresist.bsky.social for funding and supporting the collaboration with the Jenal lab!

rdcu.be/eShqI

So great to catch up with my incredible mentor and friend Alain Filloux @fillouxlab.bsky.social in Melbourne. #Bacteriology #T6SS
#Pseudomonas #Biofilm

Let's talk bacterial wars 🤺

Fresh out of the press is a new review on the #T6SS, with striking imagery and great insights into effector diversity and how this powerful nano weapon shapes #microbialcommunities

#bacterialwarfare
@springernature.com

Occurrence of type VI secretion system effector genes in longitudinal isolates of P. aeruginosa from people with cystic fibrosis Pseudomonas aeruginosa uses multiple type VI secretion systems (T6SSs) to manipulate eukaryotic cells, kill competing microbes and take up nutrients. Bacterial strains are known to differ in their T6S...

Check out our new paper in Microbial Genetics tinyurl.com/ye2azm57 showing what Type VI secretion systems are doing in chronic infections of patients with cystic fibrosis @microbiologysociety.org. Led by Antonia Habich in the Unterweger lab. #T6SS #pseudomonas @biology.ox.ac.uk

In our new article, we show how P. aeruginosa, a major cause of chronic respiratory infections in #cysticfibrosis (CF), uses the Type VI Secretion System #T6SS and specific #toxins to eliminate competing bacteria
www.cell.com/cell-reports...
#cryoEM @dshatskiy.bsky.social @jakecolautti.bsky.social

a man with a mask is holding a light saber and the website cachondeo.com is visible ALT: a man with a mask is holding a light saber and the website cachondeo.com is visible

Because GAPS4 responds to any DNA break, it’s a double-edged sword. Expose the bacterium to antibiotics or toxins (e.g., #T6SS effector) that break DNA, and GAPS4 triggers cell suicide. It’s a high-stakes trade-off between broad protection and accidental self-destruction.

Phage-encoded homing endonucleases attenuate bacterial immunity The arms race between bacteria and bacteriophages (phages) gave rise to multiple layers of antagonistic mechanisms, many of which remain unexplored. Here, we investigated the anti-phage defense system...

🚨 Happy to share our new preprint in which we explore different layers of the phage-bacteria arms race.
The highlight: phage homing endonucleases attenuate bacterial defenses 🤯
A 🧵... (1/7)
#bacteriology #antiphage #T6SS
www.biorxiv.org/content/10.1...

Excited to share that our project T6-BioSustain has been funded by @ageinves.bsky.social and @cienciagob.bsky.social ! Over the next 3 years, we'll explore the #T6SS to develop biotechnological tools for agriculture. Grateful to @ihsmumacsic.bsky.social and @univmalaga.bsky.social for support!

happy to see #T6SS MIX domain structures coming out (>10 years since we first described it)!
🦠
www.pnas.org/doi/10.1073/...

Functional replacement of ancestral antibacterial secretion system in a bacterial plant pathogen Nature Ecology & Evolution - The bacterial plant pathogen genus Xanthomonas uses two distinct secretion systems for antibacterial competition. Here the authors show that some Xanthomonas...

Very happy to announce our paper @natecoevo.nature.com on the functional replacement of ancestral antibacterial secretion system ( #T4SS #T6SS ) in a bacterial plant pathogen ( #Xanthomonas ). Enjoy reading! rdcu.be/euNrM
Special thanks to @costprogramme.bsky.social !

When bacteria get hungry, they kill—and eat—their neighbors, research reveals Scientists have discovered a gruesome microbial survival strategy: when food is scarce, some bacteria kill and consume their neighbors.

#Bacteria kill and eat their neighbors when the get #hungry ...

| #microbes | #nutrient | #Microbiomics | #disease | #T6SS | Via @sciencex.bsky.social‬

This story started when we put two Vibrio species commonly found in the coastal oceans under the microscope. V. anguillarum cannot grow on alginate, an algal polysaccharide, but V. cyclitrophicus can. So how does the former species grow? The answer: By killing the ones that can

#Microsky #T6SS

New research reveals the mode of action of the Pseudomonas aeruginosa #T6SS Tse4 toxin. Tse4 forms ion-selective, voltage-sensitive channels in bacterial membranes, coupling cell depolarization with K⁺ efflux. This highlights a key antibacterial strategy. #PFPsky
doi.org/10.1371/jour...

To make our research more approachable, I used #Gemini to develop (mostly by #vibecoding) a simulation of #T6SS mediated bacterial interactions. I hope that you'll have as much fun as I have with this and that you'll learn something new!
sites.google.com/view/bacfigh...

Had a fantastic time at @pintofscience.uk last night! Here I am wobbling on a chair trying to turn a #Phage into a #T6SS. Thanks @magdalenakurteu.bsky.social‬ for the pic!

Competitive behaviors in Serratia marcescens are coordinately regulated by a lifestyle switch frequently inactivated in the clinical environment Williams et al. discover that frequently occurring inactivating mutations in a conserved regulatory system lead to loss of competitive and pioneering behavior in clinical isolates of Serratia marcesce...

Lifestyle switch and competitive mode for Serratia marcescens. Great work from the Coulthurst lab #T6SS. Check @cp-cellhostmicrobe.bsky.social and rb.gy/l6l4ag

Outer membrane tube formation by Francisella novicida involves extensive envelope modifications and is linked with type VI secretion and alterations to the host phagosomal membrane | mBio Francisella tularensis is an intracellular bacterial pathogen that causes the zoonotic disease tularemia. Following uptake by host cells, the bacteria rapidly escape the phagosome and replicate intracellularly. In previous studies, we found that ...

Congratulations to our #postdoc Shoichi Tachiyama @yalemicropath.bsky.social‬ on his paper @mbio.bsky.social journals.asm.org/doi/10.1128/... #T6SS #cryoET

Distribution of the four type VI secretion systems in Pseudomonas aeruginosa and classification of their core and accessory effectors - Nature Communications Populations of a single bacterial species can possess a great diversity of type VI secretion systems (T6SSs) and secreted effectors. Here, Habich et al. apply molecular population genetics to the T6SS...

Up to 4 type VI secretion systems #T6SS in Pseudomonas aeruginosa 60.1. Mining genomes is always worth and a source of fine discoveries. Great work from the Unterweger lab and @lukeallsopp.bsky.social . See @natcomms.bsky.social at www.nature.com/articles/s41...

#Pseudomonas aeruginosa destroys other #bacteria using #T6SS and its effectors during infection in #cysticfibrosis patients. Here, we determined the #cryo-EM #structure of the effector Ptx2, which depolarizes target bacterial membranes.

Check it out!

www.biorxiv.org/content/10.1...

Assessing toxicity and competitive fitness of Vibrio isolates from coastal waters in Israel | mSphere The ocean’s surface water temperatures have increased in the past decades due to climate change. This increase correlates with the spread of Vibrio, a genus of aquatic bacteria, many of which are pathogens of humans and marine animals. Since Vibrio-...

Our paper on vibrios isolated from Israel's coastal waters is now online in mSphere (now with a working link). We analyzed the pathogenic potential (genome sequences, toxicity, and antibiotic resistance) of 23 new isolates.
🦠
#T6SS #T3SS #MARTX
journals.asm.org/doi/10.1128/...

Assessing toxicity and competitive fitness of Vibrio isolates from coastal waters in Israel | mSphere The ocean’s surface water temperatures have increased in the past decades due to climate change. This increase correlates with the spread of Vibrio, a genus of aquatic bacteria, many of which are path...

Our paper on vibrios isolated from Israel's coastal waters is now online in mSphere. We analyzed the pathogenic potential (genome sequences, toxicity, and antibiotic resistance) of 23 new isolates.
🦠
#T6SS #T3SS #MARTX

journals.asm.org/eprint/VBFQ3...

Evaporation controls contact-dependent bacterial killing during surface-associated growth Abstract. Many bacteria employ contact-dependent killing mechanisms, which require direct physical contact with a target cell, to gain an advantage over co

Evaporation controls contact-dependent bacterial killing during surface-associated growth

#T6SS #CoffeeRingEffect #Vcholerae

#ISMEComms by Miao Han, Chujin Ruan, Gang Wang, David R Johnson at @eawag.bsky.social and China Agricultural University

academic.oup.com/ismecommun/a...

Journées Sécrétion 2025 Contact: secretion@imm.cnrs.fr

The second edition of the 'Secretion Days' in Marseille will take place on October 2 and 3, 2025. Please spread the word!
Registration works via a Google form: forms.gle/CCyC4UXEBC55...
#Secretion | #T1SS #T2SS #T3SS #T4SS #T5SS #T6SS #T7SS

Left: WHIX can carry two flanking domains for secretion via the T6SS. AlphaFold 3 structure predictions of Awe1 (top) or Awe1 in complex with AwiU and AwiD lacking their predicted N-terminal signal peptides (bottom). The first part of the Awe1 WHIX domain is colored blue (amino acids 148–301); the second part of WHIX (amino acids 500–699) is colored magenta; the N-terminal (N-ter) Awe1 domain fused to WHIX (amino acids 1–147) is colored orange; the C-terminal (C-ter) Awe1 domain fused to WHIX (amino acids 700–862) is colored beige; AwiU is colored green; AwiD is colored purple. Right: AlphaFold structure prediction of the complex assembled by an Awe1 monomer and a VgrG4 trimer, shown as a ribbon representation. The inset is a close-up view of the predicted Awe1-VgrG4 interacting region. VgrG4 and Awe1 residues predicted to interact with each other are represented in green and orange, respectively.

Secretion mechanisms of many T6SS effectors in Gram-neg #bacteria remain unclear. @drdorsalomon.bsky.social &co identify a new class of #T6SS effectors, which can harbor either 1 or 2 toxic domains and use the WHIX domain as a secretion motif🧪 @plosbiology.org plos.io/4iCxVL3

Left: WHIX can carry two flanking domains for secretion via the T6SS. AlphaFold 3 structure predictions of Awe1 (top) or Awe1 in complex with AwiU and AwiD lacking their predicted N-terminal signal peptides (bottom). The first part of the Awe1 WHIX domain is colored blue (amino acids 148–301); the second part of WHIX (amino acids 500–699) is colored magenta; the N-terminal (N-ter) Awe1 domain fused to WHIX (amino acids 1–147) is colored orange; the C-terminal (C-ter) Awe1 domain fused to WHIX (amino acids 700–862) is colored beige; AwiU is colored green; AwiD is colored purple. Right: AlphaFold structure prediction of the complex assembled by an Awe1 monomer and a VgrG4 trimer, shown as a ribbon representation. The inset is a close-up view of the predicted Awe1-VgrG4 interacting region. VgrG4 and Awe1 residues predicted to interact with each other are represented in green and orange, respectively.

Secretion mechanisms of many T6SS effectors in Gram-neg #bacteria remain unclear. @drdorsalomon.bsky.social &co identify a new class of #T6SS effectors, which can harbor either 1 or 2 toxic domains and use the WHIX domain as a secretion motif🧪 @plosbiology.org plos.io/4iCxVL3