Scientists make bacteria breakthrough

Science

An international team of scientists led by the University of Adelaide has made a world breakthrough in understanding how bacterial toxins cause severe gastrointestinal diseases.

The scientists, led by Dr Adrienne Paton from the University of Adelaide's School of Molecular and Biomedical Science, have discovered that a highly potent bacterial toxin kills cells by inactivating an essential component in the endoplasmic reticulum (ER). The ER is part of the cell that is essential for packaging newly-synthesized proteins.

The toxin, called subtilase cytotoxin, is produced by certain strains of E. coli bacteria responsible for severe gastrointestinal disease in humans.

Dr Paton discovered the toxin in 2003 in a bacterium responsible for an outbreak of haemolytic uraemic syndrome (severe food poisoning) in South Australia.

Subtilase cytotoxin is so potent that it is a potential bio-terrorism agent.

Dr Paton and her colleagues from Monash University and Tufts New England Medical Center in Boston, United States, published their findings last month in the prestigious international journal Nature.

"The ER is a command centre of the cells of higher organisms, second only to the nucleus in its influence on other cellular functions," Dr Paton said.

"The molecule targeted by the toxin is a chaperone protein called BiP, which is a master regulator of ER function. Disrupting this crucially important chaperone has inevitably fatal consequences for a wide range of cell types."

As well as learning how the toxin works, the scientists have also determined its three-dimensional structure, which will help in the development of treatments for toxin-related diseases.

Dr Paton said the breakthrough may also provide insights into the development of age-related and degenerative diseases such as Parkinson's disease and Alzheimer's disease, which involve defects in ER function.

Scientific colleagues working on the discovery with Dr Paton include fellow researchers from the University of Adelaide, Professor James Paton and Ursula Talbot; Dr Celeste Thorpe from Tufts New England Medical Center in Boston; and Professor Jamie Rossjohn, Dr Travis Beddoe, Dr Matthew Wilce and Dr James Whisstock from Monash University.

The collaborative research was supported by the National Health and Medical Research Council and the Australian Research Council.

Story by Candy Gibson