Metal Puts a Crimp in Deadly Bacterial Toxin
by Mitch Leslie
Shiga toxin is a cellular weapon of mass destruction launched by bacterial killers. It’s responsible for everything from dysentery to deadly outbreaks of food poisoning. Researchers now report that doses of the metal manganese neutralize the poison, possibly leading to the first treatment that halts its insidious effects.
Members of the genus Shigella and several virulent strains of Escherichia coli release the shiga toxin when they invade the body. The poison injures small blood vessels and can spur our cells to kill themselves. Eating food or drinking water contaminated by shiga-producing bacteria typically causes gastrointestinal symptoms such as bloody diarrhea, and the microbes can be lethal, often by damaging the kidneys so severely that the organs shut down. Last year, for example, an outbreak of shiga-releasing E. coli that started in Germany killed some 50 people.
One reason shiga toxin is so potent is its ability to dodge cellular defenses. Cells often shunt poisons they absorb to an organelle called the lysosome for destruction. But shiga toxin takes a detour after it invades a cell, traveling to an organelle called the Golgi apparatus and eventually settling down near the cell’s protein-making machinery, which it shuts off. No treatments thwart the toxin, so doctors can only offer measures such as intravenous fluids to prevent dehydration…
(read more: Science NOW) (image: Dennis Kunkel Microscopy, Inc.)