HIV-1 Tat protein promotes formation of more-processive elongation complexes

R. A. Marciniak, P. A. Sharp

Research output: Contribution to journalArticlepeer-review

260 Scopus citations


The Tat protein of HIV-1 trans-activates transcription in vitro in a cell-free extract of HeLa nuclei. Quantitative analysis of the efficiency of elongation revealed that a majority of the elongation complexes generated by the HIV-1 promoter were not highly processive and terminated within the first 500 nucleotides. Tat transactivation of transcription from the HIV-1 promoter resulted from an increase in processive character of the elongation complexes. More specifically, the analysis suggests that there exist two classes of elongation complexes initiating from the HIV promoter: a less-processive form and a more-processive form. Addition of purified Tat protein was found to increase the abundance of the more-processive class of elongation complex. The purine nucleoside analog, 5,6-dichloro-1-β-D-ribofuranosylbenzimidazole (DRB) inhibits transcription in this reaction by decreasing the efficiency of elongation. Surprisingly, stimulation of transcription elongation by Tat was preferentially inhibited by the addition of DRB.

Original languageEnglish (US)
Pages (from-to)4189-4196
Number of pages8
JournalEMBO Journal
Issue number13
StatePublished - 1991
Externally publishedYes


  • HIV-1
  • RNA binding proteins
  • TAR
  • Tat
  • Transcription elongation

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Biochemistry, Genetics and Molecular Biology(all)
  • Immunology and Microbiology(all)


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