Modeling of the interaction between new ethidium derivatives and TAR RNA of HIV-1

During the HIV-1 replication process, interactions between the first sequence of RNA synthesized named TAR RNA and a viral protein named Tat permit a fast and efficient transcription of viral DNA in RNA. Based on the NMR structure of TAR RNA found on the PDB, new derivatives of ethidium were designed by molecular modeling to inhibit this interaction. The studied molecules are composed of three domains: an arginine, a linker, and an ethidium. Three linkers of different lengths were considered in the first step, with the TAR RNA-arginine interaction and the intercalation of the ethidium simulated by docking methods. In a second step, the structure of the TAR RNA was completed to obtain a whole ethidium interaction site and docking of the whole studied molecules was investigated. Molecules were synthesized and tested on infected cells. The predicted models and activity are in good agreement with the reported experimental results.