Genetic technology reveals how poisonous mushrooms cook...( EAST LANSING Mich. Heather Hallen s...)

EAST LANSING, Mich. Heather Hallen spent eight years looking for poison in all the wrong places.

Alpha-amanitin is the poison of the death cap mushroom, Amanita phalloides. The Michigan State University plant biology research associate was looking for a big gene that makes a big enzyme that produces alpha-amanitin, since thats how other fungi produce similar compounds. But after years of defeat, she and her team called in the big guns new technology that sequences DNA about as fast as a death cap mushroom can kill.

The results: The discovery of remarkably small genes that produce the toxin a unique pathway previously unknown in fungi.

The discovery is reported in todays Proceedings of the National Academy of Sciences. It is work that not only solves a mystery of how some mushrooms make the toxin but also sheds light on the underlying biochemical machinery. It might be possible one day to harness the mushroom genes to make novel chemicals that would be useful as new drugs.

We think we have a factory that spits out lots of little sequences to make chemicals in Amanita mushrooms, said Jonathan Walton, MSU plant biology professor who leads Hallens team. Our work indicates that these mushrooms have evolved a mechanism to make dozens or even hundreds of new, previously unknown chemicals, besides the toxins that we know about.

Of the thousands of species of mushrooms, only about 30 produce alpha-amanitin. Most of them look much like their edible cousins. But poisonous mushrooms are powerful in folklore and in history. In 54 A.D., Emperor Tiberius Claudius was fed a death cap mushroom by his wife Agrippina to put her son Nero on the throne of Rome.

Alpha-amanitin kills people by inhibiting an enzyme necessary for expression of most genes. Without the ability to synthesize new proteins, cells quickly grind to a halt. The intestinal tract and the liver are the hardest hit as they come into first contact with
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