Bacterial "poison crossbow bolts" could be used to fight antibiotic resistance
Bacteria are quickly becoming one of the greatest threats to humanity, as they evolve resistance to our best antibiotics. But scientists are starting to find that one of the most promising ways to fight bacteria is to use bacteria. Now, researchers at Imperial College London have analyzed one weapon that bacteria use to kill each other – a toxic arrowhead fired like a crossbow – which could inspire new antibiotics.
Right now, as many as 100 trillion microbes live on and in your body. As you might expect, with that many bugs vying for space, it’s anything but a peaceful world down there. Bacteria and other organisms are locked in their own arms races, constantly evolving new weapons and defenses against each other to gain the upper hand.
Scientists have been investigating how to tap into this bacterial battleground to develop new ways to protect ourselves. In recent studies, teams have made bacteria build water filters that kill other bacteria, injected predatory bugs into the body to hunt down dangerous pathogens, and pitted bacteria against each other by starving them of nutrients.
Now, a team from Imperial College London has examined one particularly clever weapon in detail. Certain bacteria species use what’s called the Type VI Secretion System (T6SS) against their rivals. T6SS acts like a molecular crossbow, firing toxic packages at other bacteria to kill them off.
The team discovered a new type of toxic “arrowhead” called VgrG2b, that the species Pseudomonas aeruginosa uses. They examined the atomic structure and found that the toxin is contained at the very tip. This turned out to be an enzyme known as a metallopeptidase.
This enzyme cuts up proteins. In this case, once it enters the unfortunate bacterial victim, it targets the area between the inner and outer membranes of the cell. This prevents the cell from dividing, and instead makes the bacteria bulge and eventually explode.
The team says that understanding this process better could help scientists develop new types of antibiotics, which are desperately needed.
“Bacteria evolved alongside each other for billions of years and have designed many strategies to fight and kill each other to prevail in the environment,” says Alain Filloux, lead author of the study. “This new ‘toxic arrowhead’ is one of the tools developed for this, and finding all the other possible strategies employed for bacterial warfare would help researchers and the pharmaceutical industry replenish the currently dwindling pipeline of antibiotics.”
The research was published in the journal Cell Reports.
Source: Imperial College London