Very cool story! Congrats!

Thanks Dor!

Overall, our findings expand our understanding of how bacteria outcompete one another in crowded environments. Check out our story! 💪

Interestingly, we found that the bacteria secreting Cpe1 are protected from self-poisoning by a protein called Cpi1. Cpi1 blocks the toxin using a unique mode. Unlike many other immunity that block the toxin’s active site, Cpi1 inhibits Cpe1 by blocking the substrate-binding site.

Using structural and mass spec approaches, we pinpointed the exact cleavage target sequences of Cpe1: in the short “double-glycine” motifs, specifically LHAGGKF, in GyrB and ParE!

This interbacterial toxin is called Cpe1. It acts like molecular scissors✂️, cutting the ATPase domains of essential topoisomerases, GyrB and ParE, in competing bacteria. Without the critical proteins, the rival cells can't properly copy their genomes, leading to growth stalls.

Link to the story: doi.org/10.1371/jour...

Bacteria are constantly fighting for survival—not just against bacteriophages, but also against each other. In our new study, we uncover an antibacterial protease toxin that bacteria frequently use to disable their rivals.

n summary, our findings show that while phage resistance helps bacteria avoid viral infection, it can come at the cost of losing the battle against other bacteria in the environment. A double-edged sword! ⚔️🔬

More interestingly, even when Salmonella was treated with an enzyme from phages that degrades LPS, it also became vulnerable to bacterial attacks, demonstrating that phages can indirectly weaken bacteria and affect bacteria-bacteria interaction.

Further experiments revealed that the O-antigen, a part of the LPS structure, is crucial for protecting Salmonella against these bacterial attacks. Without it, they became easy targets.

The reason why Salmonella lose their ability to compete is due to mutations in genes related to their cell membrane, specifically in a structure called LPS (lipopolysaccharide), which normally protects against external stresses. Bacteria with damaged LPS became vulnerable to T6S.

We used Salmonella phage-resistants as the model for the question. Interestingly, while resistant strains grew and competed normally in liquid media, they struggled when grown on solid media with bacteria with the specialized weapon: type VI secretion system (T6SS)

Bacteria can become resistant to phages that infect them, but this resistance might weaken their ability to compete with other bacteria. Here, we start by asking how phage-resistant bacteria perform in competition with other competitor bacteria.