A technique for purifying bacterial proteins in one step is invented, changing research practices.

Dr John Stocker (R), director of AMRAD, presenting institute director Sir Gustav Nossal with a cheque for the first royalty payments relating to pGEX.

By the late 1980s the institute’s booming parasitology program, led by Dr Graham Mitchell, has expanded to include studies into schistosomiasis, a neglected tropical disease caused by water-borne parasitic worms. The disease is common in Africa, Asia and South America and kills up to 200,000 people a year.

The research program, which has the goal of developing diagnostic tests for schistosomiasis, and a vaccine against the disease, also serendipitously leads to the development of a protein purification technique. The article describing the technique becomes the institute’s most cited paper1, with 5760 citations by June 2015.

Parasitic beginnings

The technique is developed by a young scientist named Dr Donald Smith, who joins the schistosomiasis team from Scotland.

The research team finds that a parasite protein called Sj26 provides some protection against schistosomiasis infection. Smith subsequently finds that the protein is part of a group of enzymes called glutathione-S-transferases (GSTs). GSTs bind tightly to a molecule called glutathione, and it was with this knowledge that Smith developed the technique that, decades later, is used routinely in thousands of laboratories around the world to purify proteins.

A laborious process

In the years before Smith’s technique was developed, there were limited options for scientists seeking an efficient protein expression and purification strategy. Although Smith wasn’t terribly interested in developing new methods2, he could see the technique might have broad application for purifying all manner of proteins, and spent his last few months in Australia working on a GST-based protein purification strategy.

Smith’s technique proved to be faster than existing approaches for purifying genetically engineered proteins, making it cheaper for scientists to produce pure protein. But its utility extended beyond making it easier to prepare protein samples. The technique also revolutionised the study of protein-protein interactions and the identification of those interactions.

Benefits crystallise

The technique was patented and then published in the journal Gene1 in 1988. Around the same time the Victorian Government established the unlisted biotech company AMRAD, with the Walter and Eliza Hall Institute as a major shareholder. AMRAD licensed the technology from the institute and developed its first commercial product – Glutagene, later called pGEX3. The product was wildly successful and by April 2002, when Chemicon International acquired the patent from AMRAD, there were more than 30 licenses for GST-based technology3.

1 Smith DB, Johnson KS. Single-step purification of polypeptides expressed in Escherichia coli as fusions with glutathione S-transferase. Gene. 1988 Jul 15;67(1):31-40.

2 Eisenstein, M. Fateful attraction. Nature Methods. 2004; 1 (3):274-274.

3 Mitchell, G.F., Davern, K.M, and Tiu, W.U. (2008). The Schistosoma japonicum – based pGEX vector: an example of commercial outcomes from analysis of model host-parasite relationships in a long-term “North-South” collaboration. The Open Parasitology Journal. 2: 43-46.

View related events
Graham Mitchell enables institute scientists “to go where the parasites actually are”.