Molecule Keeps Pathogens in Check

Scientists at UT Southwestern Medical Center found that the molecule LED209 interferes with the biochemical signals that cause bacteria in our bodies to release toxins.

In the new study, UT Southwestern researchers describe how LED209 blocks the bacterial receptor QseC sensor kinase, which is found in the membrane of a diarrhea-causing strain of Escherichia coli. This receptor receives signals from human flora and hormones in the intestine that cause the bacteria to initiate infection.

In studies in vitro, Dr. Sperandio and her colleagues found that LED209 blocked the QseC sensors in E. coli, Salmonella and Francisella tularensis bacteria, preventing them from expressing virulence traits. Using mice models of infection, the researchers also showed that LED209 blocks pathogenesis of Salmonella and F. tularensis, preventing them from causing disease in these animals.

Unlike conventional antibiotics, which work by killing bacteria, LED209 allows the pathogen to grow but not become virulent and make the host sick. Dr. Sperandio said killing the bacteria or inhibiting their growth just “angers” some bacteria and causes them to release toxins.

“The sensors in bacteria are waiting for the right signal to initiate the expression of virulent genes,” she said. “Using LED209, we blocked those sensing mechanisms and basically tricked the bacteria to not recognize that they were within the host. When we did that, the bacterial pathogens could not effectively cause disease in the treated animals.”

Source: Newswise