H-1-NMR STUDIES OF THE HIGH-AFFINITY REV BINDING-SITE OF THE REV RESPONSIVE ELEMENT OF HIV-1 MESSENGER-RNA - BASE FAIRING IN THE CORE BINDING-ELEMENT

H-1 NMR studies of a 30-nucleotide RNA oligonucleotide (RBE3), which c ontains a high-affinity binding site for Rev of the HIV-1 Rev responsi ve element (RRE), two derivatives of RBE3 (RBE3AA and RBE3-A), and the complex of RBE3 with peptides derived from the RNA binding domain of HIV-1 Rev, are presented. The high-affinity binding site of the RRE co nsists of an asymmetric internal loop and surrounding Watson-Crick bas e pairs. In the wild-type RRE, one of the stems is closed by a loop; t his is replaced in REB3 by the stable UUCG tetraloop. NOE data suggest that the internal loop of the free RNA contains structural features t hat have been predicted on the basis of in vitro selection experiments [Bartel, D. P., et al. (1991) Cell 67, 529-536]. The structural featu res include a G(syn).G(anti) base pair, a G(anti).A(anti) base pair, a nd a looped out U. When the Rev peptide is bound to the RNA, the base pairs in the internal loop appear to be stabilized, although the RNA c hemical shifts indicate that the RNA conformation undergoes some chang es when bound by Rev peptide.