Sequence-specific binding of DNA and RNA to immobilized Nickel ions

• DOI: 10.1016/j.bbrc.2007.11.169
• Publication Date: 2008-01-02T22:32:33Z
• Authors: Branislav Nastasi...; Nicole A. Becker; Susan E. Wurster; L. James Maher
• Keywords: Nitrilotriacetic acid; Divalent; Aptamer

Immobilization of divalent Nickel cations provides a tool for affinity purification of proteins containing hexahistidine tags. During experiments to generate single-stranded DNA aptamers to immobilized proteins we inadvertently identified DNA sequences with affinity for Nickel-nitrilotriacetic acid (Ni(2+)-NTA) magnetic beads. Analysis of these aptamers revealed that affinity for the Ni(2+)-NTA support requires only single-stranded sequences with multiple adenosine residues. Bound nucleic acids can be eluted with imidazole. A single-stranded dA(20) affinity tag (but not other homopolymer sequences) is sufficient for immobilization of double-stranded DNA PCR products on Ni(2+)-NTA magnetic beads. Addition of an rA(20) sequence to an RNA transcript allowed its affinity capture on Ni(2+)-NTA magnetic beads, suggesting an approach for purification of poly(A) mRNA.