HIV-1 Trans-Activator of Transcription protein (Tat)

The HIV-1 Trans-Activator of Transcription (Tat) protein is a small, multifunctional regulatory protein encoded by the tat gene in the HIV-1 genome[2][3]. Tat is essential for efficient HIV-1 replication as it dramatically increases the efficiency of viral transcription by binding to the TAR (trans-activation response) RNA element at the 5' end of viral mRNA and recruiting cellular cofactors such as Cyclin T1 and CDK9, forming the P-TEFb complex that phosphorylates RNA polymerase II to enhance transcription elongation[1][2][3]. Tat also modulates cellular gene expression, impacts the immune response, is released extracellularly from infected cells, and contributes to HIV pathology by inducing apoptosis in uninfected bystander cells and playing a role in development of HIV-associated neurocognitive disorders[1][2][3]. Tat is a canonical example of a viral transcription factor that interacts with RNA instead of DNA[3]. It remains a focus for therapeutic intervention in HIV infection and associated comorbidities, although no current medicines directly target Tat in clinical practice.

Other names

Trans-Activator of TranscriptionTat proteinHIV Tat proteinHIV-1 Tat

Inhibitors block Tat’s interaction with the TAR RNA element or disrupt recruitment of positive transcription elongation factor b (P-TEFb), thereby reducing HIV transcription and replication[1][4].