The researchers studied a mechanism of action they call the "magic spot" an important regulator of gene expression. They describe their results in the current issue of the journal Cell.

Researchers know that the magic spot a molecule known as guanosine-tetraphosphate or ppGpp is involved in how bacteria respond to amino acid starvation. More recently, researchers have discovered that ppGpp is an important part of pathogens that cause illnesses such as cholera and Legionnaires' disease.

A cell makes ppGpp when amino acid levels are low.

"Microbiologists have wondered for a half-century how this small molecule with a relatively simple structure could have such a profound effect on regulating a cell's survival," said Irina Artsimovitch, a study co-author and an assistant professor of microbiology at Ohio State University. She collaborated on this work with study lead author Dmitry Vassylyev, of the RIKEN Institute in Japan.

ppGpp controls what researchers call the "stringent response" a condition of nutritional starvation. When amino acid pools in a cell are exhausted, ppGpp accumulates and shuts down the synthesis of new proteins. The cell goes dormant until amino acid levels return to normal.

By learning the structure of ppGpp and how it interacts with the enzyme RNA polymerase the main enzyme that controls gene expression in a cell the researchers were able to describe in detail the "magic" behind the magic spot, Artsimovitch said.

"This study sheds a good deal of light on the inner workings of the molecular machinery that carries out gene expression in bacteria," she said. "Knowing this can serve as a basis for a new type of antibiotics.

In related work reported in a recent issue of the Journal of Bacteriology, Artsimovitch led a team of researche
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Contact: Irina Artsimovitch
Artsimovitch.1@osu.edu
614-292-6777
Ohio State University
29-Apr-2004