SOLUTION STRUCTURE OF A BOVINE IMMUNODEFICIENCY VIRUS TAT-TAR PEPTIDE-RNA COMPLEX

The Tat protein of bovine immunodeficiency virus (BIV) binds to its ta rget RNA, TAR, and activates transcription. A 14-amino acid arginine-r ich peptide corresponding to the RNA-binding domain of BIV Tat binds s pecifically to BIV TAR, and biochemical and in vivo experiments have i dentified the amino acids and nucleotides required for binding, The so lution structure of the RNA-peptide complex has now been determined by nuclear magnetic resonance spectroscopy. TAR forms a virtually contin uous A-form helix with two unstacked bulged nucleotides. The peptide a dopts a beta-turn conformation and sits in the major groove of the RNA . Specific contacts are apparent between critical amino acids in the p eptide and bases and phosphates in the RNA. The structure is consisten t with ail biochemical data and demonstrates ways in which proteins ca n recognize the major groove of RNA.