Office of Science Research Yields Understanding of Key Function of Uranium-Reducing Microbe


Biophysical research has provided an important clue about how bacteria move within radionuclide-contaminated sites, where they can reduce and immobilize these contaminants. Scientists at Argonne National Laboratory determined the three-dimensional structure of sensory domains of two proteins involved in movement of the bacterium Geobacter sulfurreducens. These domains are involved in chemotaxis, the means by which bacteria sense where to move to find nutrients or to avoid harmful chemicals. Binding of a stimulant molecule to a sensory domain on the outside of the cell transmits a signal to the interior of the cell, initiating the expression of proteins that enable the cell to move in response to the external stimulation. The Geobacter family is of particular interest because it is a major component of the microbial community in many subsurface environments contaminated by uranium. The Office of Science is supporting research into how Geobacter affects fate and transport of uranium in order to understand how this contamination could be remediated. The information obtained about the structure of the signaling domains will help to understand not only how microbes sense and move toward locations with higher uranium concentrations, but more generally respond to a variety of chemical changes in their environment. The Argonne research was led by Dr. Marianne Schiffer of the Biosciences Division and made use of the Structural Biology Center’s protein crystallography stations at the Advanced Photon Source. It was published in the April 11, 2008, issue of the Journal of Molecular Biology.