Selective Nucleic Acid Capture with Shielded Covalent Probes
Nucleic acid probes are used for diverse applications in vitro, in situ, and in vivo. In any setting, their power is limited by imperfect selectivity (binding of undesired targets) and incomplete affinity (binding is reversible, and not all desired targets bound). These difficulties are fundamental, stemming from reliance on base pairing to provide both selectivity and affinity. Shielded covalent (SC) probes eliminate the longstanding trade-off between selectivity and durable target capture, achieving selectivity via programmable base pairing and molecular conformation change, and durable target capture via activatable covalent cross-linking. In pure and mixed samples, SC probes covalently capture complementary DNA or RNA oligo targets and reject two-nucleotide mismatched targets with near-quantitative yields at room temperature, achieving discrimination ratios of 2–3 orders of magnitude. Semiquantitative studies with full-length mRNA targets demonstrate selective covalent capture comparable to that for RNA oligo targets. Single-nucleotide DNA or RNA mismatches, including nearly isoenergetic RNA wobble pairs, can be efficiently rejected with discrimination ratios of 1–2 orders of magnitude. Covalent capture yields appear consistent with the thermodynamics of probe/target hybridization, facilitating rational probe design. If desired, cross-links can be reversed to release the target after capture. In contrast to existing probe chemistries, SC probes achieve the high sequence selectivity of a structured probe, yet durably retain their targets even under denaturing conditions. This previously incompatible combination of properties suggests diverse applications based on selective and stable binding of nucleic acid targets under conditions where base-pairing is disrupted (e.g., by stringent washes in vitro or in situ, or by enzymes in vivo).
Additional Information© 2013 American Chemical Society. ACS AuthorChoice. Received: January 27, 2013; Published: June 7, 2013. We thank Dr. Peng Yin for discussions, Victoria Hsiao for performing additional characterizations of photoreversal conditions, Dr. Joshua Day for synthesis of alternative photocross-linkers, Dr. Le Trinh for providing plasmid pCS2+mCherry:H2B and Maayan Schwarzkopf for providing plasmid pTNT-DsRed2. This work was funded by NIH 5R01CA140759, NIH P50 HG004071, the Caltech Innovation Initiative, the Caltech Programmable Molecular Technology Initiative via Grant GBMF2809 from the Gordon and Betty Moore Foundation, an NSF Graduate Research Fellowship (H.M.N.), and a Ford Foundation Predoctoral Fellowship (H.M.N.).
Published - ja4009216.pdf
Supplemental Material - ja4009216_si_001.pdf