NMR spectroscopy has emerged as a powerful and reliable tool not only to study the
structure of macromolecules but also to detect interactions between RNA and partners (proteins, RNA or small molecules). We used NMR to decipher the first events of the HIV-1 reverse transcription. Indeed, in retroviruses, a cellular tRNA that is encapsidated in viral particles primes initiation of reverse transcription. tRNALys
3 is the natural primer of all immunodeficiency viruses, including HIV-1. The formation
of the reverse transcription initiation complex (viral RNA/tRNALys3) requires the fusion of the three-dimensional structure of tRNA, an event that does not occur spontaneously at physiological temperature of the host, but requires the action of the nucleocapsid protein (NC). Using NMR spectroscopy, we were able to gain access to a dynamic view of the formation of the initiation complex and to identify milestones and conformational changes undergone by these RNAs. To our knowledge, this is the first detailed mechanistic analysis of a molecular rearrangement of RNA studied at the level of each base pair. In parallel, we also used NMR to develop an original method for designing RNA ligands. As proof of concept, we developped tRNALys 3 ligands using a fragment-based approach. Fragment evolution and linker selection were guided by NMR, recent results will be discussed.

Invité par Philippe Fossé

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