Branched and multi-chain nucleic acid switches for sensing and screening
First Claim
1. A method of chemical screening comprising:
- providing a bistable branched switch, comprising DNA, RNA, modified nucleic acid, or combinations thereof, wherein the branched switch is adapted to switch from a first conformation to a second conformation upon ligand binding, said switch comprising;
a probe strand P comprising a ligand binding domain;
a switching framework comprising a cover strand (C), which is partially but not completely complementary to P;
a tether that holds P and C together while the switch changes between the first and second conformations without dissociating the branched nucleic acid thereby creating a rapidly reversible switch;
a toggle strand (T) tethered to the P-strand and the C-strand by covalent linkage; and
a signaling apparatus comprising a combination of signaling entities, wherein a ligand for the ligand binding domain is selected from the group consisting of proteins, cell-surface features, and small molecules, and wherein the ligand binding domain is sequestered in the first conformation;
contacting the branched switch with the ligand in the absence of a screened chemical entity;
monitoring a signal produced from the signaling apparatus in the absence of the chemical entity;
contacting the branched switch with the ligand in the presence of the chemical entity;
monitoring a signal produced from the signaling apparatus in the presence of the chemical entity; and
comparing the signal produced in the absence of the chemical entity with the signal produced in the presence of the chemical entity to determine the effect of the chemical entity on the ligand binding.
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Abstract
Embodiments of the invention relate to a branched or multichain nucleic acid switch adapted to switch from a first conformation to a second conformation upon ligand binding. The switch includes a probe strand, P, which includes the ligand binding domain; a switching framework which includes a cover strand (C), and a tether that holds P and C together and a signaling apparatus. Some embodiments include a toggle strand (T) where now the tether holds P, C, T, and the signaling apparatus together. As the switch changes between the first and second conformations; the signaling apparatus reports the state of the switch. The signaling entity is typically a lumiphore and a quencher located along the switching framework. Nucleic acid switches have applications in real time assays for diverse agents including infectious agents, environmental toxins, and terrorist agents, as well as screening methods for such agents. Further applications are found for nanoelectronics, nanofabrication and nanomachines.
13 Citations
20 Claims
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1. A method of chemical screening comprising:
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providing a bistable branched switch, comprising DNA, RNA, modified nucleic acid, or combinations thereof, wherein the branched switch is adapted to switch from a first conformation to a second conformation upon ligand binding, said switch comprising; a probe strand P comprising a ligand binding domain; a switching framework comprising a cover strand (C), which is partially but not completely complementary to P; a tether that holds P and C together while the switch changes between the first and second conformations without dissociating the branched nucleic acid thereby creating a rapidly reversible switch; a toggle strand (T) tethered to the P-strand and the C-strand by covalent linkage; and a signaling apparatus comprising a combination of signaling entities, wherein a ligand for the ligand binding domain is selected from the group consisting of proteins, cell-surface features, and small molecules, and wherein the ligand binding domain is sequestered in the first conformation; contacting the branched switch with the ligand in the absence of a screened chemical entity; monitoring a signal produced from the signaling apparatus in the absence of the chemical entity; contacting the branched switch with the ligand in the presence of the chemical entity; monitoring a signal produced from the signaling apparatus in the presence of the chemical entity; and comparing the signal produced in the absence of the chemical entity with the signal produced in the presence of the chemical entity to determine the effect of the chemical entity on the ligand binding. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of chemical screening comprising:
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providing a bistable multichain switch, comprising DNA, RNA, modified nucleic acid, or combinations thereof, wherein the switch comprises a ligand binding domain and a signaling apparatus and, wherein the multichain switch is adapted to switch from a first conformation to a second conformation upon ligand binding, and wherein said switch comprises; a first strand comprising the ligand binding domain; a second strand; and a fastener to couple the two strands together without dissociating the multichain switch, thereby creating a rapidly reversible switch; wherein the first strand and second strand hybridize to each other in the first conformation which sequesters the ligand binding domain and the ligand binding domain is free in the second conformation, wherein a ligand for the ligand binding domain is selected from the group consisting of proteins, cell-surface features, and small molecules; contacting the multichain switch with the ligand in the absence of a screened chemical entity; monitoring a signal produced from the signaling apparatus in the absence of the chemical entity; contacting the multichain switch with the ligand in the presence of the chemical entity; monitoring a signal produced from the signaling apparatus in the presence of the chemical entity; and comparing the signal produced in the absence of the chemical entity with the signal produced in the presence of the chemical entity to determine the effect of the chemical entity on the ligand binding. - View Dependent Claims (11, 12, 13, 14, 15)
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9. A method of chemical screening comprising:
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providing a bistable multichain switch, comprising DNA, RNA, modified nucleic acid, or combinations thereof, wherein the multichain switch is adapted to switch from a first conformation to a second conformation upon ligand binding, said switch comprising; a probe strand P comprising a ligand binding domain; a switching framework comprising a cover strand (C), which is partially but not completely complementary to P; a tether that holds P and C together while the switch changes between the first and second conformations without dissociating the multichain nucleic acid thereby creating a rapidly reversible switch; and a signaling apparatus comprising a combination of signaling entities, wherein a ligand for the ligand binding domain is selected from the group consisting of proteins, cell-surface features, and small molecules, and wherein the ligand binding domain is sequestered in the first conformation, wherein tethering occurs via a fastener duplex, F, to couple two covalently linked nucleic acid strands together by a non-covalent interaction, wherein the first strand comprises C and the second strand comprises P when the multichain switch is in the second conformation; contacting the multichain switch with the ligand in the absence of a screened chemical entity; monitoring a signal produced from the signaling apparatus in the absence of the chemical entity; contacting the multichain switch with the ligand in the presence of the chemical entity; monitoring a signal produced from the signaling apparatus in the presence of the chemical entity; and comparing the signal produced in the absence of the chemical entity with the signal produced in the presence of the chemical entity to determine the effect of the chemical entity on the ligand binding. - View Dependent Claims (10, 16, 17, 18, 19, 20)
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Specification