CA150, a nuclear protein associated with the RNA polymerase II holoenzyme, is involved in Tat-activated human immunodeficiency virus type 1 transcription

Carlos Suñe, Takuma Hayashi, Yi Liu, William S. Lane, Richard A. Young, Mariano A. Garcia-Blanco

Research output: Contribution to journalArticle

80 Scopus citations

Abstract

Maximal human immunodeficiency virus type 1 (HIV-1) gene expression requires specific cellular factors in addition to the virus-encoded trans- activator protein Tat and the RNA element TAR. We developed a functional assay, based on transcriptional activation in vitro, to identify these cellular factors. Here, we describe the purification and molecular cloning of CA150, a nuclear protein that is associated with the human RNA polymerase II holoenzyme and is involved in Tat-dependent HIV-1 transcriptional activation. The sequence of CA150 contains an extensive glutamine- and alanine-rich repeat that is found in transcriptional modulators such as GAL11 and SSN6 in Saccharomyces cerevisiae and Zeste in Drosophila melanogaster. Immunodepletion of CA150 abolished Tat trans activation in vitro. Moreover, overexpression of a mutant CA150 protein specifically and dramatically decreased Tat-mediated activation of the HIV-1 promoter in vivo, strongly suggesting a role for CA150 in HIV-1 gene regulation. Immunoprecipitation experiments demonstrated that both CA150 and Tat associate with the RNA polymerase II holoenzyme. Furthermore, we found that functional Tat associates with the holoenzyme whereas activation-deficient Tat mutants do not. Thus, we propose that Tat action is transduced via an RNA polymerase II holoenzyme that contains CA150.

Original languageEnglish (US)
Pages (from-to)6029-6039
Number of pages11
JournalMolecular and Cellular Biology
Volume17
Issue number10
DOIs
StatePublished - Oct 1997
Externally publishedYes

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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