Incorporation of a non-nucleotide bridge into hairpin oligonucleotides capable of high-affinity binding to the Rev protein of HIV-1.

A bridge containing a rigid trans-stilbene group, -P(O)(O-)O(CH2)3NHC(O)- C6H4-CH=CHC6H4C(O)NH(CH2)3OP(O)(O-)-, has been incorporated into several oligonucleotide sequences based on the minimal Rev Binding Element (RBE) of HIV-1. This bridge was found to be effective as a UUCG tetraloop in stabilizing short RNA duplex structures containing mismatched bases and bulged out nucleotide residues and to be more effective than either a TTTT loop or a triethyleneglycol linker in stabilizing similar DNA structures. Evaluation of stilbene-containing RNA RBE sequences of varying length for their ability to bind the Rev protein of HIV-1 showed that a 22-nucleotide stilbenedicarboxamide conjugate bound Rev almost as well as a 94-base fragment of the Rev Responsive Element (RRE). A DNA hairpin mimetic with the same sequence was incapable of Rev binding. Taken together, these experiments serve as an example for how in vitro selection and chemical modification can be combined to generate high-affinity mimetics of nucleic acid sequence and structure.