Frog peptides versus superbugs

Neutrons and native frogs are an unlikely but dynamic duo in the battle against antibiotic-resistant bacteria, commonly known as superbugs, recent research has shown.

The skin secretions of the Australian green-eyed and growling grass frogs contain peptides (small proteins) that help frogs fight infection. Researchers hope these peptides will offer a new line of defence against a range of human bacterial pathogens, including methicillin-resistant Staphylococcus aureus (MRSA).

New research conducted by the University of Melbourne together with the Australian Nuclear Science and Technology Organisation (ANSTO) is revealing how and why these peptides kill bacterial cells while leaving animal cells—frog or human—untouched.

ANSTO biophysicist Dr Anton Le Brun studies synthetic versions of these peptides at the molecular level using the “Platypus” neutron reflectometer. Neutron reflectivity analysis provides a picture of the structure and function of the peptides.

“We’re getting an insight into how a particular peptide is interacting with the bacterium membrane and ultimately resulting in its death,” says Anton. “We can locate where the peptide is in the membrane and look at the structural changes.”

Unlike current antibiotics, which typically interrupt bacterial function, these frog peptides kill bacteria by attacking the lipid components of the cell membrane, punching holes in it or breaking it down. Because these peptides damage structure, rather than function, the development of resistance to antibiotics based on these peptides is reduced.

Anton and his colleagues hope this knowledge will lead to the design of powerful antibiotics that are less prone to bacterial resistance—a new phase in the battle against superbugs.

Photo: The growling grass frog’s skin secretions include disease fighting peptides.
Credit: Craig Cleeland

Australian Nuclear Science and Technology Organisation, Anton Le Brun, Tel: +61 2 9717 9921,,

Story written for Science in Public as part of Stories of Australian Science 2012

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