Researchers discover new toxin that impedes bacterial growth

November 06, 2019

HAMILTON, ON (Nov. 6, 2019) - An international research collaboration has discovered a new bacteria-killing toxin that shows promise of impacting superbug infectious diseases.

The discovery of this growth-inhibiting toxin, which bacteria inject into rival bacteria to gain a competitive advantage, was published today in the journal Nature.

The discovery is the result of teamwork by co-senior authors John Whitney, assistant professor of the Department of Biochemistry and Biomedical Sciences at McMaster University, and Mike Laub, professor of biology at the Massachusetts Institute of Technology (MIT).

Whitney and his PhD student Shehryar Ahmad at McMaster's Michael G. DeGroote Institute for Infectious Disease Research were studying how bacteria secrete antibacterial molecules when they came across a new toxin. This toxin was an antibacterial enzyme, one the researchers had never seen before.

After determining the molecular structure of this toxin, Whitney and Ahmad realized that it resembles enzymes that synthesize a well-known bacterial signalling molecule called (p)ppGpp. This molecule normally helps bacteria survive under stressful conditions, such as exposure to antibiotics.

"The 3D structure of this toxin was at first puzzling because no known toxins look like enzymes that make (p)ppGpp, and (p)ppGpp itself is not a toxin," said Ahmad.

Suspecting the toxin might kill bacteria by overproducing harmful quantities of (p)ppGpp, the McMaster team shared their findings with Laub, an investigator of the U.S. Howard Hughes Medical Institute.

Boyuan Wang, a postdoctoral researcher in the Laub lab who specializes in (p)ppGpp signaling, examined the activity of the newly discovered enzyme. He soon realized that rather than making (p)ppGpp, this enzyme instead produced a poorly understood but related molecule called (p)ppApp. Somehow, the production of (p)ppApp was harmful to bacteria.

The researchers determined that the rapid production of (p)ppApp by this enzyme toxin depletes cells of a molecule called ATP. ATP is often referred to as the 'energy currency of the cell' so when the supply of ATP is exhausted, essential cellular processes are compromised and the bacteria die.

"I find it absolutely fascinating that evolution has essentially "repurposed" an enzyme that normally helps bacteria survive antibiotic treatment and, instead, has deployed it for use as an antibacterial weapon," said Whitney.

The research conducted at McMaster University was funded by the Canadian Institutes for Health Research and is affiliated with the CIHR Institute for Infection and Immunity (CIHR-III) hosted at McMaster University with additional funding from the David Braley Centre for Antibiotic Discovery. The research at MIT was supported by the Howard Hughes Medical Institute and the U.S. National Institutes of Health.

"This is an important discovery with potential implications for developing alternatives to antibiotics, a global priority in the fight against antimicrobial resistance. It is heartening to see that young Canadian researchers like Dr. Whitney are thriving and emerging as leaders in this area," said Charu Kaushic, scientific director of the CIHR-III and a professor of pathology and molecular medicine at McMaster.
-end-
Editors: Photos of co-senior authors John Whitney, assistant professor of the Department of Biochemistry and Biomedical Sciences at McMaster University, and Mike Laub, professor of biology at the Massachusetts Institute of Technology (MIT) are attached.

For more information or to arrange an interview, please contact:

Veronica McGuire
Media Relations
Faculty of Health Sciences
McMaster University
vmcguir@mcmaster.ca
905-525-9140, ext. 22169

Raleigh McElvery
Department of Biology
Massachusetts Institute of Technology
mcelvery@mit.edu
617-258-0494

McMaster University

Related Bacteria Articles from Brightsurf:

Siblings can also differ from one another in bacteria
A research team from the University of Tübingen and the German Center for Infection Research (DZIF) is investigating how pathogens influence the immune response of their host with genetic variation.

How bacteria fertilize soya
Soya and clover have their very own fertiliser factories in their roots, where bacteria manufacture ammonium, which is crucial for plant growth.

Bacteria might help other bacteria to tolerate antibiotics better
A new paper by the Dynamical Systems Biology lab at UPF shows that the response by bacteria to antibiotics may depend on other species of bacteria they live with, in such a way that some bacteria may make others more tolerant to antibiotics.

Two-faced bacteria
The gut microbiome, which is a collection of numerous beneficial bacteria species, is key to our overall well-being and good health.

Microcensus in bacteria
Bacillus subtilis can determine proportions of different groups within a mixed population.

Right beneath the skin we all have the same bacteria
In the dermis skin layer, the same bacteria are found across age and gender.

Bacteria must be 'stressed out' to divide
Bacterial cell division is controlled by both enzymatic activity and mechanical forces, which work together to control its timing and location, a new study from EPFL finds.

How bees live with bacteria
More than 90 percent of all bee species are not organized in colonies, but fight their way through life alone.

The bacteria building your baby
Australian researchers have laid to rest a longstanding controversy: is the womb sterile?

Hopping bacteria
Scientists have long known that key models of bacterial movement in real-world conditions are flawed.

Read More: Bacteria News and Bacteria Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.