Superstars of STEM: Beating bacteria at its own game


Queensland’s Róisín McMahon is looking to nature for clues to overcoming antibiotic resistance. Dion Pretorius reports.


Róisín McMahon is working her way through a library of biological samples in search of ways to defeat bacterial infection.
Róisín McMahon is working her way through a library of biological samples in search of ways to defeat bacterial infection.
STA

Each year about 700,000 people across the globe die from drug resistant bacterial infections.

Antibiotics are becoming less effective as bacteria increasingly escape one of our most powerful modern medicines, making antimicrobial resistance one of humanity’s most pressing challenges.

Work is underway to find novel and innovative ways to tackle the problem, and Róisín McMahon from Griffith University in Queensland is looking at compounds found in Australia to do so.

The first part of her research uses X-ray crystallography to understand the molecular structure of bacterial proteins, and how chemical compounds interact with them. This provides insights into how the protein functions and how bacteria are able to cause disease. The results may expose possible chinks in the microbial ‘armour’.

Next, she uses Nature Bank – a library that holds more than 45,000 chemical mixtures sourced from Australian plants and marine life – to identify compounds that can change how a protein works, or even stop it working completely.

She explains that the library may allow her to develop new compounds, leading eventually to new medicines that alter how the protein behaves with therapeutic benefit.

The way bacteria do harm is by causing an infection in the body, using a variety of protein “weapons”. Many of these are assembled by a central folding enzyme called disulfide bond protein-A. It acts on proteins, assembling them and adding structural bracing important for their function.

McMahon says if she can identify a chemical that prevents this central enzyme from working, she believes she can stop the bacteria’s ability to cause infection.

“What’s exciting,” she explains, “is that this approach doesn’t threaten the life of the bacteria, which means resistance might not develop as rapidly, or indeed at all, and these treatments could be effective for much longer than we have seen previously.”

McMahon says that in addition to addressing antimicrobial resistance, her work could also lead to new treatments for diseases that are difficult to treat using current medicines.

Melioidosis, for example, is a rare tropical infection that is extremely challenging to treat, because it is naturally very resistant to many antibiotics. McMahon hopes that her approach may unlock ways to tackle it.

“We’re still not sure what sort of treatments will be unlocked by analysing this bank of biological specimens,” she says.

“But Australian flora and fauna could hold the key to addressing some of the world’s greatest modern medical challenges, just one of them being antimicrobial resistance.”


Róisín McMahon is among 30 Superstars of STEM featured in this weekly series prepared by Science & Technology Australia (STA). To learn more about the program, visit the STA website.

  1. https://amr-review.org/
  2. https://cosmosmagazine.com/biology/fears-about-antibiotic-resistance-have-opened-up-a-can-of-germs
  3. https://www.griffith.edu.au/institute-drug-discovery/unique-resources/naturebank
  4. https://www.researchgate.net/profile/Robert_Cumming2/publication/8670621_Protein_Disulfide_Bond_Formation_in_the_Cytoplasm_during_Oxidative_Stress/links/02e7e526fecb552847000000/Protein-Disulfide-Bond-Formation-in-the-Cytoplasm-during-Oxidative-Stress.pdf
  5. http://conditions.health.qld.gov.au/HealthCondition/condition/14/33/455/melioidosis
  6. https://scienceandtechnologyaustralia.org.au/what-we-do/superstars-of-stem/
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