RE-SELEX: restriction enzyme-based evolution of structure-switching aptamer biosensors |
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Authors: | Aimee A Sanford Alexandra E Rangel Trevor A Feagin Robert G Lowery Hector S Argueta-Gonzalez Jennifer M Heemstra |
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Institution: | Department of Chemistry, Emory University, Atlanta Georgia 30322 USA.; Department of Chemistry, Center for Cell and Genome Science, University of Utah, Salt Lake City Utah 84112 USA ; BellBrook Labs, LLC, Madison Wisconsin 53711 USA |
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Abstract: | Aptamers are widely employed as recognition elements in small molecule biosensors due to their ability to recognize small molecule targets with high affinity and selectivity. Structure-switching aptamers are particularly promising for biosensing applications because target-induced conformational change can be directly linked to a functional output. However, traditional evolution methods do not select for the significant conformational change needed to create structure-switching biosensors. Modified selection methods have been described to select for structure-switching architectures, but these remain limited by the need for immobilization. Herein we describe the first homogenous, structure-switching aptamer selection that directly reports on biosensor capacity for the target. We exploit the activity of restriction enzymes to isolate aptamer candidates that undergo target-induced displacement of a short complementary strand. As an initial demonstration of the utility of this approach, we performed selection against kanamycin A. Four enriched candidate sequences were successfully characterized as structure-switching biosensors for detection of kanamycin A. Optimization of biosensor conditions afforded facile detection of kanamycin A (90 μM to 10 mM) with high selectivity over three other aminoglycosides. This research demonstrates a general method to directly select for structure-switching biosensors and can be applied to a broad range of small-molecule targets.RE-SELEX is the first homogenous method for in vitro evolution of structure-switching DNA aptamers. |
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