Australian researchers have found that Human immune proteins that is essential for fighting viruses and bacterial infections and cancer is part of the ancient and lethal toxin family found in bacteria which causes disease like anthrax, gas gangrene and scarlet fever. The protein called perforins was discovered a team led by Professor James Whisstock and Dr Michelle Dunstone from Monash University's School of Biomedical Sciences.
Professor Whisstock, winner of the 2006 Science Minister's Prize for Life Scientist of the Year, said the team was stunned when it became clear that the bacterial toxins and perforins had a common ancestor. "Over millions of years of evolution bacteria developed these proteins as weapons of attack," he said. "But animals have evolved these proteins for defence against that attack. It's a molecular arms race and there's still no clear winner."
Professor Whisstock said perforins were so-called because they kill bacteria, virally-infected cells and cancerous cells by punching tiny holes that perforate them. "People who lack one of these perforins can develop a serious blood disease called hemophagocytic lymphohistiocytosis and may be predisposed to develop cancer," he said.
Dr Dunstone said the findings were the culmination of nine years of research. "Now we finally know what perforins look like and how they work, we can use this knowledge to develop new ways to fight disease," she said.
Professor Whisstock said certain perforins were not only important for defending humans against attack by bacteria and viruses, but also important for propagating the human species because of their role in embryo implantation. "It is ironic that we fear diseases such as anthrax yet from the same family of toxins comes a protein that is involved in reproduction," he said.
The research team included scientists from the National Health and Medical Research Council's protease systems biology program, the Australian Research Council's Centre of Excellence in Structural and Functional Microbial Genomics and the Peter MacCallum Cancer Centre. The X-ray data was collected at the Advanced Photon Source in Chicago.