A garden insect makes a molecule that attacks the cell wall of bacteria, providing a new potential weapon in the fight against antibiotic resistance.
Thanatin is a peptide molecule produced by the spined soldier bug Podisus maculiventris to control the types of bacteria that live in its gut. A research group from the University of Zurich found that thanatin kills the bacteria Escherichia coli by blocking vital proteins in the bacterial cell wall.
E. coli is amongst the bacteria considered critically important targets for new drugs due to their increasing resistance to current antibiotics. Thanatin could, therefore, give us more options for treating E. coli infections.
The study, published in Science Advances, used a combination of techniques including microscopy and nuclear magnetic resonance imaging to visualize exactly how the insect molecule thanatin kills bacteria. It found that thanatin kills the gram-negative bacteria E. coli by disrupting proteins vital for forming its outer membrane, which is necessary for the bacteria to survive.
Thanatin is part of a new class of antibiotics that interfere with the outer membrane of gram-negative bacteria. New classes of antibiotics are needed for gram-negative bacteria because fewer antibiotics affect them. In fact, no new class of antibiotics has been approved for gram-negative bacteria since 1968.
“This is an unprecedented mechanism of action for an antibiotic and immediately suggests ways to develop new molecules as antibiotics targeting dangerous pathogens,” stated John Robinson, a researcher from the University of Zurich, and one of the authors of the study.
The Swiss biopharmaceutical Polyphor, an industrial partner of Robinson’s research group, is currently developing antibiotics for gram-negative bacteria based on the new class of antibiotics. The company expects to have candidate drugs in the clinic by 2019.
A number of companies in Europe have joined the fight against antibiotic resistance in healthcare. One project by AiCuris targets gram-negative bacteria and is currently in Phase I. Some companies are ditching traditional antibiotic molecules altogether and going for approaches such as bacteria-eating viruses or the gene-editing technology CRISPR-Cas9.
Images from Shutterstock and Robert Webster, Wikimedia Commons (CC BY-SA 4.0)