Figure 10.
Heterogeneous transcriptional start site usage modulates HIV-1MAL RNA dimerization and function. (A) Three guanines (red) can serve as alternative transcription start sites. (B) Transcripts are co-transcriptionally capped by 7-methylguanosine. (C) Effect of 5′-guanosines and capping on 5′-leader dimerization. (D) Portions of 2D NOE spectra showing similarities of Cap-CH3 to Cap-H8, G3, and G108 NOEs observed for G8 intact dimer and the Capped TAR-polyA-U5AUG (Cap1G-leaderTPUA). (E) Assigned A-H2 NOEs and deduced secondary structure; discrete functional elements differentiated by color. Dashed lines denote residues of the Cap1G-leaderTPUA construct used for high-resolution structural studies. (F) Structure of the Cap1G-leaderTPUA showing end-to-end stacking of the TAR and polyA helices and sequestration of the Cap. Adapted from [75], with permission.