Book mechanism identified as communication method for bacterial toxins

Researchers have uncovered the unique method a certain bacteria uses to deliver toxins.

Scientists at Binghampton University, State University of New York, uncovered how the gram-negative bacterium communicates through transporting small molecules. The understanding of these mechanisms could help to design better methods of controlling and blocking these toxins.

Assistant Professor Xin Yong and graduate student Ao Li from the Department of Mechanical Engineering, along with Associate Professor Jeffrey W. Schertzer from the Department of Biological Sciences worked on the study.

The research team mentioned how the communication molecules stimulate the production of outer membrane vesicles, and how these ‘packages’ that contain highly concentrated toxins, bud off from the surface of the bacterium. The researchers wanted to work on a model to understand more about how the communication molecule inserts itself into the membrane of bacteria to physically stimulate the production of the toxin delivery vesicles. 

“It’s hard to see the molecular detail at that level,” explained Prof Schertzer. “But with Dr Yong’s expertise, we were able to build a computational model that helped us understand what actually goes on between individual molecules.”

The model allowed the team to identify details of the molecule, and understand its reaction with the membrane.

“Our most important finding is that the communication molecule needs to enter the membrane in a very specific way,” said Prof Schertzer. “It folds itself like a book, then will expand once it has entered the membrane.”

“Gram-negative bacteria likely all have similar types of communication molecules. We focused on the PQS [Pseudomonas Quinolone Signal] molecule of Pseudomonas aeruginosa because it was the first discovered and is the best studied,” said Dr Yong. “Other Gram-negative species, such as E. coli, may be transferring their own communication molecules in a similar way.”

“This study was a testament to how beneficial interdisciplinary work can be,” said Prof Schertzer. “We had reached a limit with what could be done experimentally and needed Dr Yong’s model to develop a rationale for how the molecule was interacting with the membrane. Most importantly, this work has generated a wealth of new questions that we are now continuing to investigate.”

The study was published in the Journal of Biological Chemistry.