[Univ. of Illinois] [School of Chemical Sciences] [Dept. of Chemistry] [Organic Chemistry] [Chemical Biology]
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Allosteric nucleic acid enzymes (aptazymes) as practical sensors
Nucleic acid enzymes may be engineered as sensors. The basic concept is to develop allosteric nucleic acid enzymes ("aptazymes"), for which the catalytic activity is regulated by the binding of a ligand at a site remote from the active site. When the change in catalytic activity upon ligand binding is coupled with a useful form of signal readout, such as that based on fluorescence or color, then a practical sensor device has been created. In collaboration with two other research groups on the UIUC campus, the Silverman lab is creating aptazyme sensors for compounds of agricultural or other importance.
Aptazyme sensors for fungal toxins
We are developing aptazyme sensors for toxins produced by fungi; i.e., mycotoxins. Some of these toxins, such as the aflatoxins, fumonisin B1 (FB1), vomitoxin (deoxynivalenol; DON), and zearalenone (ZEN), are of considerable agricultural importance because the fungi that produce these compounds can infect crops such as peanuts, corn, and wheat. The detection of small concentrations of the toxins would allow early identification of fungal contamination, and appropriate remedial steps could then be initiated.
A three-part strategy for creating the aptazyme sensors
To create aptazyme sensors for these mycotoxins, we are implementing a three-part strategy. In the first part of the project, we are developing allosteric deoxyribozymes for which the catalytic activity is responsive to the presence of a specific toxin. This will be accomplished by identifying DNA aptamers (DNA sequences that bind) to the toxins, followed by joining these aptamers to known deoxyribozymes to render them allosterically sensitive to the toxin. Alternatively, deoxyribozymes with catalytic activities that are allosterically regulated by a toxin will be identified directly. In both strategies, in vitro selection will be used to identify the functional DNA sequences.
In the second part of the project, the aptazymes will be integrated with convenient signal readout systems. This work is in collaboration with Prof. Yi Lu of our department, who has developed sensor systems that are based on either fluorescence or on gold nanoparticles, which lead to a colorimetric response. An example of an aptazyme with fluorescence signaling capability is shown below. Finally, in the third part of the project, the aptazyme sensors will be used in field applications, in collaboration with Prof. Henry Wilkinson of the Turfgrass Program in the UIUC Department of Natural Resources and Environmental Sciences (NRES).
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Research description last updated January 26, 2008