Platypus milk may help fight superbugs: study

Platypus milk has unique proteins with antibacterial properties that may prove to be an unlikely hero in the global fight against drug-resistant pathogens.

Due to its unique features - duck-billed, egg-laying, beaver-tailed and venomous- the platypus has long exerted a powerful appeal to scientists, making it an important subject in the study of evolutionary biology.

In 2010 scientists discovered that platypus milk contained unique antibacterial properties that could be used to fight superbugs.

Researchers at Commonwealth Scientific and Industrial Research Organization (CSIRO) and Deakin University in Australia have solved a puzzle that helps explain why platypus milk is so potent - bringing it one step closer to being used to save lives.

The discovery was made by replicating a special protein contained in platypus milk in a laboratory setting.

"Platypus are such weird animals that it would make sense for them to have weird biochemistry," said Janet Newman, CSIRO scientist.

"The platypus belongs to the monotreme family, a small group of mammals that lay eggs and produce milk to feed their young," said Newman, lead author of the study published in the journal Structural Biology Communications.

"By taking a closer look at their milk, we've characterised a new protein that has unique antibacterial properties with the potential to save lives," she said.

Using X-ray crystallography, the team discovered a unique structure in the platypus milk protein which, when solved, formed a three-dimensional fold, similar to a ringlet.

As platypus do not have teats, they express milk onto their belly for the young to suckle, exposing the mother's highly nutritious milk to the environment, leaving babies susceptible to the perils of bacteria.

Researchers believed this was why the platypus milk contained a protein with rather unusual and protective antibacterial characteristics.

"We were interested to examine the protein's structure and characteristics to find out exactly what part of the protein was doing what," said Julie Sharp at Deakin University.

Researchers successfully made the protein, then deciphered its structure to get a better look at it. They found a unique, never-before-seen 3D fold.

Due to its ringlet-like formation, researchers have dubbed the newly discovered protein fold the 'Shirley Temple', in tribute to the former child actor's distinctive curly hair.

"Although we've identified this highly unusual protein as only existing in monotremes, this discovery increases our knowledge of protein structures in general, and will go on to inform other drug discovery work done at the Centre," she said.

In 2014 the World Health Organisation released a report highlighting the scale of the global threat posed by antibiotic resistance, pleading for urgent action to avoid a "post-antibiotic era", where common infections and minor injuries which have been treatable for decades can once again kill.