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

Journal Article

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.

Full Text

Duke Authors

Cited Authors

  • Suñé, C; Hayashi, T; Liu, Y; Lane, WS; Young, RA; Garcia-Blanco, MA

Published Date

  • October 1997

Published In

Volume / Issue

  • 17 / 10

Start / End Page

  • 6029 - 6039

PubMed ID

  • 9315662

International Standard Serial Number (ISSN)

  • 0270-7306

Language

  • eng

Conference Location

  • United States