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.
Rajendran
Manjula
M
Department of Chemistry and Biochemistry, Institute for Cell and Molecular Biology, University of Texas at Austin, 2500 Speedway, Austin, TX 78712, USA.
Ellington
Andrew D
AD
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