Selective recognition and cleavage of RNA loop structures by Ni(II)•Xaa-Gly-His metallopeptides

The recognition and cleavage of tRNA(Phe) and the TAR RNA of HIV-1 by metallopeptides of the general form Ni(II). Xaa-Gly-His (where Xaa is Gly, Lys, or Arg) were investigated. The results of RNA cleavage analyses suggest that KHSO5- or magnesium monoperoxyphthalate-activated metallopeptides (1) induce nucleobase damage which requires aniline acetate for complete RNA strand scission and (2) selectively target the loops of stem-loop structures of the above-named substrates. In targeting RNA loop regions, the metallopeptides may be sensitive to intraloop structural features, including the overall structural environment of the loop itself and possibly the presence of intraloop hydrogen bonding. Overall, these results suggest that the metallopeptides interact selectively within a loop, in a fashion reminiscent of many RNA binding proteins, instead of targeting RNA single-stranded character alone. These observations further suggest a possible metallopeptide-based strategy for the molecular recognition of native RNA structures and insight with regard to the general features available for ligand binding site discrimination.