DNA Catalysts with Tyrosine Kinase Activity

ABSTRACT: We show that DNA catalysts (deoxyribo-zymes, DNA enzymes) can phosphorylate tyrosine residues of peptides. Using in vitro selection, we identified deoxyribozymes that transfer the γ-phosphoryl group from a 5′-triphosphorylated donor (a pppRNA oligonucleotide or GTP) to the tyrosine hydroxyl acceptor of a tethered hexapeptide. Tyrosine kinase deoxyribozymes that use pppRNA were identified from each of N30, N40, and N50 random-sequence pools. Each deoxyribozyme requires Zn2+, and most additionally require Mn2+. The deoxy-ribozymes have little or no selectivity for the amino acid identities near the tyrosine, but they are highly selective for phosphorylating tyrosine rather than serine. Analogous GTP-dependent DNA catalysts were identified and found to have apparent Km(GTP) as low as ∼20 μM. Thes