Emory Report homepage  

November 10, 2008
Glycomics Center facilitates a surprising discovery about red meat

By Quinn Eastman

Humans who eat red meat are vulnerable to bacteria that cause food poisoning because their cells incorporate an otherwise foreign sugar molecule from the meat, an international team of researchers has discovered. A toxin from the bacteria sticks to the foreign sugar molecules, which are found on the surface of the human cells.

Emory biochemist David Smith played a critical role in putting together the research team that made this surprising observation, which was published in the Oct. 30 issue of Nature.

“One of the researchers and authors, James C. Paton from the University of Adelaide in Australia, sent a protein toxin to Emory to be analyzed on our glycan microarray,” Smith says.

The Australian researchers were studying subtilase cytotoxin, which comes from certain kinds of E. coli bacteria. Bacterial production of the toxin and subsequent binding and entry of toxin into intestinal cells causes bloody diarrhea and a potentially fatal disease called haemolytic uraemic syndrome. Humans usually become infected after eating contaminated red meat, which is why the syndrome is also known as
“hamburger disease.”

The glycan microarray, housed in the Emory Glycomics Center, allows researchers to test whether proteins stick to a large variety of carbohydrate molecules (glycans), which are found on the surface of animal cells.
“When I noticed that this toxin, which was supposed to be toxic to humans, bound tightly to glycans containing N-glycolylneuraminic acid, a non-human carbohydrate,” Smith says, “I put Dr. Paton in touch with Ajit Varki, an expert at the University of California San Diego in studies on N-glycolylneuraminic acid. The resulting collaboration is a nice example of how the Emory Glycomics Center and the international Consortium for Functional Glycomics have facilitated discovery.”

The study combines Emory data on which sugars the toxin binds to, animal studies at University of California San Diego, and protein structural studies in Australia.

The Emory Glycomics Center houses the Protein-Carbohydrate Interaction Core H of the Consortium for Functional Glycomics, a research initiative funded by the National Institute of General Medical Sciences of the National Institutes of Health. Smith is the director of Core Facility H.