Figure 11.

NMR and structural findings for the monomeric ^Cap3G and ^Cap2G forms of the HIV-1_MAL leader. (A) Regions of the 2D ¹H-¹H NOESY spectra for the non-capped 3G- leader³⁷¹ (A^H, black; A^2rG^r, green; A^2rC^r, blue; G1^HA^2r, red) used to make secondary structure assignments shown in D. (B) Overlapped 2D ¹H-¹H NOESY spectra for A²-^Cap2G-leader³⁷¹ (black) and TAR fragment ^Cap2G-TAR^m (dashed outlined residues in panel D with U13 and G47 connected by a GAGA tetraloop) (red), showing that the cap methyl group is in close proximity to A58. (C) Similar results were obtained for ^Cap3G-leader³⁷¹ (black) and a ^Cap3G-TAR^m RNA (red). (D) NOEs (arrows) and secondary structure of monomeric Cap-3G HIV-1_MAL leader. (E) Structure of a ^Cap3G-TAR^m showing the unstructured Cap. Adapted from [75], with permission.