Synthesis of aminoglycoside-3'-conjugates of 2'-O-methyl oligoribonucleotides and their invasion to a 19F labeled HIV-1 TAR model

The potential of aminoglycosides to induce RNA-invasion has been demonstrated. For this purpose, aminoglycoside-3'-conjugates of 2'-O-methyl oligoribonucleotides have been synthesized entirely on a solid phase. The synthesis includes an automated oligonucleotide chain elongation to solid-supported neomycin, ribostamycin, and methyl neobiosamine, and a two-step deprotection/release of the solid-supported conjugate, which allows exploitation of a simple protecting group scheme. Conjugates have been targeted to a (19)F labeled HIV-1 TAR RNA model (Trans Activation Response element of HIV), which allows monitoring of the invasion by (19)F NMR spectroscopy. A remarkably enhanced invasion, compared to that resulting from the corresponding unmodified 2'-O-methyl oligoribonucleotide (5'-CAGGCUCA-3'), has been obtained by the neomycin conjugate. The increased affinity results from a cooperative binding of the neomycin moiety and hybridization, though the invasion may also follow a mechanism, in which the first molar equivalent of the conjugate induces hybridization of the second.