OCT 19, 2018 10:34 AM PDT

A Newly Discovered Bacterial Toxin Reveals More About Bacterial Warfare

WRITTEN BY: Carmen Leitch

Even bacteria have to use self-defense. Some deploy toxins that they can utilize to dominate other microbial competitors. Researchers have discovered a new bacterial toxin that is different from others we've found. The scientists were surprised to see that this toxin, called Tre1, acts like the ones made by cholera, pertussis, and diphtheria, but instead of against human cells, they use Tre1 against other bacteria. The findings have been reported in Cell.

Healthy cells (left) and cells under attack by the newly discovered toxin (right). The protein targeted by the toxin is labeled with green fluorescent protein. The toxin disrupts the structure made by this protein at the center of the cell. Without this structure, cells cannot divide. Instead, they grow longer until eventually they break apart and die.  / Credit: Mougous Lab/UW Medicine

"What is special about this toxin is that it acts by the same biochemical mechanism as some infamous toxins employed by human pathogens, which evolved much later than the toxins bacteria use against each other," explained UW Medicine microbiologist Brook Peterson. Peterson works in the lab of Joseph Mougous, professor of microbiology and biochemistry at the University of Washington School of Medicine in Seattle.

Bacterial toxins can disrupt essential proteins inside the host cells it invades. Cholera, for example, interferes with cells in the gut, causing them to release far too much water and salt, which results in severe diarrhea. Of course, bacteria won’t get diarrhea, but when they are exposed to the Tre1 toxin, they exhibit signs of serious illness.

The researchers used the microbe Serratia proteamaculans to learn more about bacterial competition. This microbe can live in tree roots or encourage plant growth. It can also reside in the gastrointestinal tract of different animals, and can also grow in food, where it causes spoilage.

Microbes often have to compete for resources, so when too many bacteria show up, the herd must be culled so others can survive. Tre1 helps kill off bacteria, reducing the population so S. proteamaculans can live. “The toxin we have discovered targets a protein, called FtsZ, that is essential for cells to divide," Peterson revealed. When this protein is blocked, the intoxicated cells grow longer and longer, she noted. Those cells eventually break open and die.  

Bacteria that use this toxin, however, have to be impervious to its effects or else it won’t do much good for them to use it. The team identified a protein the bacteria make to counteract it, shielding themselves.

"This protein protects the bacterium from both the toxin it produces itself and from toxins that function by the same mechanism but made by other species," Peterson added.

This work offers us a close look at the offensive and defensive strategies employed in bacterial warfare. It also reveals more about how these infections cause problems for people. 

The researchers suggest that when bacterial competition heats up, it can induce the creation of new tactics and the birth of new toxins.

"Research such as this can offer clues to the evolutionary origins of the potent toxins that bacterial pathogens use to cause disease," Peterson said. "It also provides a fascinating example of the complex strategies bacteria employ in their constant battle for survival with their microbial neighbors." 

Learn more about how cholera toxins work from the video.


Sources: AAAS/Eurekalert! Via University of Washington Health Science/UW Medicine, Cell

About the Author
  • Experienced research scientist and technical expert with authorships on 28 peer-reviewed publications, traveler to over 60 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
You May Also Like
MAY 15, 2020
Immunology
Support the Microbiome So the Immune System Can Do Its Job
MAY 15, 2020
Support the Microbiome So the Immune System Can Do Its Job
Research has long connected the human microbiome and immune system function, and now a recent study pinpoints a key poin ...
JUN 01, 2020
Microbiology
The Most Common Marine Microbe Has a Virus in Its Genome
JUN 01, 2020
The Most Common Marine Microbe Has a Virus in Its Genome
Single-celled ocean microbes known as Pelagibacter or SAR11 make up about 25 percent of the plankton on the planet.
JUN 01, 2020
Genetics & Genomics
Vaping Increases Oral Disease Risk After Only a Few Months
JUN 01, 2020
Vaping Increases Oral Disease Risk After Only a Few Months
E-cigarettes have emerged as a healthier alternative to smoking, but many studies have suggested that vaping still poses ...
JUL 27, 2020
Microbiology
Vikings Carried, and Helped Spread Smallpox
JUL 27, 2020
Vikings Carried, and Helped Spread Smallpox
A global vaccination effort led to the official eradication of smallpox, but not before it killed over 300 million peopl ...
AUG 02, 2020
Microbiology
Examining the Existence of Organelles in Bacteria
AUG 02, 2020
Examining the Existence of Organelles in Bacteria
Cells can be grouped into two general categories: prokaryotic, which make up microbes like bacteria and archaea, or euka ...
AUG 05, 2020
Microbiology
Revealing the Secrets of a Symbiotic Relationship
AUG 05, 2020
Revealing the Secrets of a Symbiotic Relationship
Some salamanders (Ambystoma maculatum) have a strange relationship with a type of alga (Oophila amblystomatis): they are ...
Loading Comments...