HIV-1 TAR RNA – Tat transactivation complex (Tat-TAR complex) (Tat-TAR complex)

The HIV-1 TAR RNA – Tat transactivation complex is a pivotal regulatory assembly essential for the high-level expression of the human immunodeficiency virus type 1 (HIV-1) genome [1, 11]. It is formed when the viral Trans-activator of transcription (Tat) protein binds to the Trans-activation response (TAR) element, a stable stem-loop RNA structure located at the 5' end of all nascent viral transcripts [11, 14]. This interaction serves as a molecular switch that recruits the host's positive transcription elongation factor b (P-TEFb) complex, comprising CDK9 and Cyclin T1, to the viral promoter [8, 12]. The recruitment of P-TEFb facilitates the phosphorylation of the RNA polymerase II C-terminal domain, thereby overcoming transcriptional pausing and promoting the synthesis of full-length viral RNAs [11, 13]. In the context of disease, the Tat-TAR complex is indispensable for viral replication and the progression of HIV-1 infection to AIDS [6, 10]. Because this interaction is unique to the virus and lacks a direct human homolog, it is an attractive target for the development of "block and lock" functional cure strategies [1, 8]. Therapeutic efforts focus on small molecules, cyclic peptides, and RNA-binding ligands designed to disrupt the binding interface, particularly at the TAR bulge or the Tat arginine-rich motif [1, 5, 14]. Inhibiting this complex effectively silences viral transcription, potentially preventing the reactivation of latent viral reservoirs and reducing the chronic inflammation associated with persistent Tat expression [1, 11].

Other names

Tat-TAR interactionHIV-1 transactivation complexTat-TAR RNA complexHIV-1 TAR-Tat complexTrans-activation response element – Trans-activator of transcription complex

Inhibition of the interaction between the HIV-1 Tat protein and the TAR RNA element to prevent the recruitment of the P-TEFb complex and subsequent transcriptional elongation of the viral genome.