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
DEC 05, 2018
DEC 05, 2018
Human Gut Bacteria Found to Carry Over 6000 Antibiotic Resistance Genes
The human body is home to vast numbers of microbes, and many of them harbor interesting genes....
DEC 11, 2018
Genetics & Genomics
DEC 11, 2018
Dust with High Levels of Triclosan has More Antibiotic Resistance Genes
Researchers have found that some dust contains high amounts of a common antimicrobial agent called triclosan....
DEC 12, 2018
Cell & Molecular Biology
DEC 12, 2018
Study Shows Why Diets Rich in Red Meat Increase Heart Disease Risk
For decades, we've known that red meat is a risk factor for heart disease. Now, researchers at the Cleveland Clinic know why....
DEC 19, 2018
Health & Medicine
DEC 19, 2018
Mastitis: An Unwanted Complication for the New Mother
  Mastitis, occurring in approximately 1-3% of new mothers, is an unexpected bump in the road for those with newborns. Breastfeeding is a crucial time...
JAN 04, 2019
JAN 04, 2019
Greenland Ice Sheet Found to Release Tons of Methane
Methane is a greenhouse gas considered to be 20-28 times more powerful than carbon dioxide....
JAN 16, 2019
JAN 16, 2019
Identifying Microbes That can Generate Electricity
Some microbes might be hugely beneficial to humans, such as in the production of energy and biofuels....
Loading Comments...