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School Accolades

Mining Lifesaving Secrets

Valeria Culotta

Metallobiologist Valeria Culotta tracks our cells’ precious metals.

Ever wonder why the nutritional-content labels for some foods include mention of zinc, copper or manganese—elements forged in the hearts of ancient stars, and best known to us as ingredients in coins and wires and steel? As it turns out, all life—even single-celled bacteria—needs these metals to survive.

“And of course you can’t make them, you’ve got to get them from the environment,” says Valeria Culotta, PhD, a professor and a “metallobiologist” in Biochemistry and Molecular Biology as well as Environmental Health Sciences.

Culotta began research in this field in the late 1980s, and last December was made a fellow of the American Academy for the Advancement of Science (AAAS), in recognition of her pioneering work on the cellular processes that deliver such metals where they are needed.

These processes are crucial because zinc, copper and manganese, as well as their better-known cousin, iron, help cells cope with oxygen—a key player in efficient energy production, but also a highly reactive element that can damage DNA and other cell parts. Certain cellular enzymes can disarm hazardous oxygen-containing molecules, but these enzymes need atoms of metal to do their work. “The antioxidant enzyme is basically inert until it gets its metal,” says Culotta.

But how does such an enzyme get its metal—and precisely the metal it needs? “In a test tube, one of these enzymes will take up such metals indiscriminately; they all look alike to it,” she says. “Yet the enzyme usually will work properly only with a particular metal; the wrong one will kill it.”

Culotta and others have shown that there are specific metallochaperone proteins within cells that grab these metals and deliver them to the appropriate enzymes. Culotta has produced dozens of papers in this field, and is best known for her work in identifying metallochaperones that deliver copper to key antioxidant enzymes known as superoxide dismutases.

“We’ve been doing the very basic biology, using mostly yeast as a model organism, to define the genes and proteins that make up these metal-trafficking pathways,” Culotta says. Yeast is a single-celled organism and therefore relatively easy to study in the lab—and as Culotta and her colleagues have found, the genes involved in metal-trafficking appear to be so important evolutionarily that they are almost always found in similar forms in both lower and higher organisms.

Almost always. And the exceptions could represent an opportunity. “We’re now looking at how these metal-trafficking pathways differ in some disease-causing bacteria and fungi,” she says. “To the extent that they differ, they could be disrupted using drugs, thus killing these pathogens without harming the analogous pathways in humans.”

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