Tat acetylation: a regulatory switch between early and late phases in HIV transcription elongation

Novartis Found Symp. 2004;259:182-93; discussion 193-6, 223-5.

Abstract

The HIV transcriptional activator Tat enhances the processivity of RNA polymerase II by recruiting the CyclinT1/CDK9 complex to the TAR RNA element. In addition, Tat synergizes with the histone acetyltransferase p300 and is acetylated by p300 at a single lysine residue (K50) in the TAR RNA binding domain. We have recently reported that this post-translational modification is necessary for the interaction and transcriptional synergy of Tat with the transcriptional coactivator PCAF. We have further studied the relevance of Tat acetylation during HIV transcription and generated antibodies specific for acetylated Tat (AcTat). Microinjection of anti-AcTat antibodies inhibited Tat-mediated transactivation in cells. Similarly, the specific p300 inhibitor Lys-CoA and short inhibitory RNAs specific for p300 suppressed Tat transcriptional activity. Full-length synthetic AcTat bound to TAR RNA and CyclinT1 with high affinity, but formation of the Tat-TAR-CyclinT1 ternary complex was inhibited when K50 was acetylated. Our data collectively show that Tat acetylation by p300 defines a critical step in Tat transactivation that serves to disrupt the Tat/TAR/CyclinT1 complex and helps in recruiting PCAF to the elongating RNA polymerase II.

Publication types

  • Review

MeSH terms

  • Acetylation
  • Acetyltransferases / metabolism*
  • Cell Cycle Proteins / metabolism*
  • Gene Expression Regulation, Viral / physiology*
  • Gene Products, tat / metabolism*
  • HIV / genetics*
  • HIV / physiology
  • Histone Acetyltransferases
  • Humans
  • Transcription Factors
  • Transcription, Genetic / physiology*
  • p300-CBP Transcription Factors
  • tat Gene Products, Human Immunodeficiency Virus

Substances

  • Cell Cycle Proteins
  • Gene Products, tat
  • Transcription Factors
  • tat Gene Products, Human Immunodeficiency Virus
  • Acetyltransferases
  • Histone Acetyltransferases
  • p300-CBP Transcription Factors
  • p300-CBP-associated factor