Selection of fluorescent aptamer beacons that light up in the presence of zinc.
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.
Department of Chemistry and Biochemistry, Institute for Cell and Molecular Biology, University of Texas at Austin, 2500 Speedway, Austin, TX 78712, USA.
Manjula
M
Rajendran
Andrew D
AD
Ellington
D052157:Aptamers, Nucleotide / Q000737:chemistry*; D001483:Base Sequence; D004277:DNA, Single-Stranded / Q000737:chemistry; D009690:Nucleic Acid Conformation; D013050:Spectrometry, Fluorescence; D015032:Zinc / Q000737:chemistry*
D052157:Aptamers, Nucleotide; D004277:DNA, Single-Stranded; D015032:Zinc