Carnivorous mushrooms share secrets

Carnivorous oyster mushrooms feed on spiders and roundworms using the toxic protein pleurotolysin, which punches holes in cells.

In what is the culmination of seven years of work, an international team of researchers has revealed the molecular process behind the protein’s hole-making ability.

Led by the ARC Imaging Centre at Monash University in Melbourne and Birkbeck College in London, the team took molecular snapshots of pleurotolysin in action and turned these into a movie.

Pleurotolysin is made up of two parts, a lipid- or membrane-binding PlyA protein and a pore-forming MACPF component PlyB.

Using a combination of synchrotron light and cryo-electron microscopy, along with biophysical and computational experiments, the researchers found that 13 identical copies of the pleurotolysin protein self-assemble into a giant tunnel.

The molecular movie reveals how the pleurotolysin protein latches onto a target cell and undergoes a conformational change to breach the cell membrane - killing the cell directly or providing a passage for other proteins that can kill it.

“I never believed I’d be able to see these proteins in action,” said lead author Dr Michelle Dunstone in a statement. “It’s an amazing mechanism, and also amazing that we now have the technology to see these hole-punching proteins at work.”

The molecular movie reveals how the pleurotolysin protein latches onto a target cell and unfolds and refolds putting a hole in it - killing the cell directly or providing a passage for other proteins that can kill it.

The researchers plan to look at equivalent proteins in other species such as perforin, a cytotoxic protein found in T lymphocytes in humans which they believe will behave in the same way as pleurotolysin.

Other potential applications for these proteins include as new drug targets and new tools for medicine, agriculture, genetic engineering and nano-engineering.

The research has been published in PLOS Biology