A New Class of HIV-1 Tat Antagonist Acting through Tat−TAR Inhibition

• Published in: Biochemistry (Easton) 1998-04, Vol.37 (15), p.5086-5095
• Main Authors: Hamy, François, Brondani, Vincent, Flörsheimer, Andreas, Stark, Wilhelm, Blommers, Marcel J. J, Klimkait, Thomas
• Format: Article
• Language: English
• Subjects: Acridines - pharmacology; AIDS/HIV; Anti-HIV Agents - pharmacology; Base Sequence; Drug Design; Gene Products, tat - antagonists & inhibitors; Gene Products, tat - metabolism; HIV-1; Molecular Sequence Data; Protein Binding - drug effects; RNA, Messenger - metabolism; RNA, Viral - metabolism; Structure-Activity Relationship; tat Gene Products, Human Immunodeficiency Virus
• ISSN: 0006-2960; 1520-4995
• DOI: 10.1021/bi972947s

The main transcriptional regulator of the human immunodeficiency virus, the Tat protein, recognizes and binds to a small structured RNA element at the 5‘ end of every viral mRNA, termed TAR. On the basis of published structural data of the molecular interactions between TAR and Tat-related peptides, we defined requirements for potential low-molecular weight inhibitors of TAR recognition by the Tat protein. In accordance with the resulting concept, a series of compounds was synthesized. In vitro evaluation of their potential to directly interfere with Tat−TAR interaction was used to define a new chemical class of potent Tat antagonistic substances. The most active compound competed with Tat−TAR complexation with a competition dose CD50 of 22 nM in vitro and blocked HIV expression in a cellular Tat transactivation system with an IC50 of 1.2 μM. The close relation between structural features of the interaction between TAR and a new type of inhibitory agent, “In-PRiNts” (for inhibitor of protein−ribonucleotide sequences), such as CGP 40336A and those of the Tat−TAR complex was confirmed by RNase A footprinting and by two-dimensional NMR. Structural implications for the complex between this class of compounds and TAR RNA will be presented.