Bacteria can sense in their environments changes in molecular concentrations as small as 0.1 percent, the equivalent of one drop diluted in a pool of a 1,000 drops. How do they do it?

New Cornell research, highlighted on the cover of the May issue of Nature Structural and Molecular Biology, reveals that receptors assemble into a kind of cooperative lattice on a bacterium's surface to amplify infinitesimal changes in the environment and kick off processes that lead to specific responses within the cell.

"Bacteria sense a lot of different things. But assume it's a sugar molecule that a bacterium needs as a nutrient -- even a 0.1 percent change in concentration can be detected, and this sensitivity is maintained over five orders of magnitude in nutrient concentration," said Brian Crane, assistant professor of chemistry and chemical biology and corresponding author of the paper. "Biologically, I know of no other system that is so sensitive over such a large range."

Crane believes the kind of cooperative lattice found in bacterial receptors may in fact point to a general mechanism for cellular signaling and serve as inspiration for developing molecular devices. Such devices could be used to sense a wide range of chemicals, light, ionic strength (salt), pH and heavy metals with great sensitivity, gain and dynamic range. Scientists are interested in developing synthetic systems with such sensing properties as well as engineering bacteria that respond to stimuli such as pollutants or explosives.

Using a combination of X-ray crystallography to determine the structure of receptors and enzymes and a novel spectroscopic technique fo
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Contact: Krishna Ramanujan
ksr32@cornell.edu
607-255-3290
Cornell University News Service
1-Jun-2006