HIV-1 TAT protein

Cysteine core NLS
FUNCTION
    Plays a role in transcription activation of the HIV-1 promoter and regulates the switch between active transcription and latency. Recognizes TAR RNA sequence on nascent HIV RNAs and recruits the cyclin T1-CDK9 complex that will in turn hyperphosphorylate the RNA polymerase II to allow efficient elongation. TAT also recruits the histone acetyltransferases (HATs) CREBBP, EP300 and PCAF to the chromatin to provide a favorable environement for viral transcription. When provirus emerge from latency, the initial rounds of transcription are very limited until new TAT synthesis occurs after about 2 hours.
INTERACTIONS
    P-TEFB complex through the cyclin T1 subunit
    Acetyltransferase P300/CBP
SUBCELLULAR LOCATION
  • Host cytoplasm
  • Host nucleus
TIMING OF EXPRESSION
    Early
Host protein Modification Residue(s) Proposed effect Reference
PRMT6 Arginine methylation R52 Reduced interaction with the TAR region of viral RNA
PRMT7 Arginine methylation R53 Reduced interaction with the TAR region of viral RNA
PCAF Lysine acetylation K28 Reduced TAT activity to promote microtubule assembly
P300/CBP Lysine acetylation K50 Reduced TAT ability to bind the TAR RNA element
MDM2 Lysine ubiquitination K71 Increased TAT transcriptional activity
CDK2 Serine phosphorylation S16 Increased TAT transcriptional activity
CDK2 Serine phosphorylation S46 Increased TAT transcriptional activity