Selection of fluorescent aptamer beacons that light up in the presence of zinc |
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Authors: | Manjula Rajendran Andrew D. Ellington |
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Affiliation: | (1) MBB 3.424, Department of Chemistry and Biochemistry, Institute for Cell and Molecular Biology, University of Texas at Austin, 2500 Speedway, Austin, TX 78712, USA |
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Abstract: | In order to generate nucleic acid biosensors that could undergo a reversible conformation change in the presence of the metal zinc, a random sequence pool of single-stranded DNA was immobilized on an oligonucleotide affinity column. In the presence of zinc, those species that underwent a conformational change were released from the column, collected, and amplified. A series of negative and positive selections refined the metal specificity of the selected aptamer beacons. Since the aptamer beacons contained a fluorophore, while the bound oligonucleotide contained a quencher, zinc binding also resulted in an increase in fluorescence. One of the selected beacons, Zn-6m2, bound zinc in the low micromolar range, gave a dose-dependent fluorescence signal, and showed an approximately sixfold increase in fluorescence on zinc binding. While some cross-reactivity with cadmium was observed, it should nonetheless prove possible to use the novel selection method to generate and tune the specificity of a variety of reversible metal biosensors. Such biosensors could potentially be used for continuous monitoring of metals in environmental samples. |
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Keywords: | Aptamer In vitro selection SELEX Biosensor Zinc Conformational switch |
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