Figure 6.
Kissing and extended duplex forms of dimeric DIS. (A,B) Secondary structures of the HIV-1NL4-3 DIS element in kissing (A) and extended duplex (B) conformations. Individual RNAs denoted in red and blue. The palindrome and flanking purines of the apical loop (Loop C) are colored yellow and pink, respectively. Residue numbers correspond to that of a truncated construct utilized in (D). (C) Solution NMR structure of a DIS kissing dimer. (D) Solution NMR structure of the extended dimer. Flanking purines (red) stack to form a zipper motif. (E) Structure of the extended duplex form of DIS, as determined by a hybrid NMR/cryo-EM approach. Panels (C–E) reproduced from [202,203,204], respectively, with permission.