title: The human immunodeficiency virus transactivator Tat interacts with the RNA polymerase II holoenzyme.
abstract: The human immunodeficiency virus (HIV) encodes a transcriptional transactivator (Tat), which binds to an RNA hairpin called the transactivation response element (TAR) that is located downstream of the site of initiation of viral transcription. Tat stimulates the production of full-length viral transcripts by RNA polymerase II (pol II). In this study, we demonstrate that Tat coimmunoprecipitates with the pol II holoenzyme in cells and that it binds to the purified holoenzyme in vitro. Furthermore, Tat affinity chromatography purifies a holoenzyme from HeLa nuclear extracts which, upon addition of TBP and TFIIB, supports Tat transactivation in vitro, indicating that it contains all the cellular proteins required for the function of Tat. By demonstrating that Tat interacts with the holoenzyme in the absence of TAR, our data suggest a single-step assembly of Tat and the transcription complex on the long terminal repeat of HIV.
authors.affiliation: Department of Medicine, University of California at San Francisco, 94143-0724, USA.
authors.forename: T P
authors.initials: TP
authors.lastname: Cujec
authors.forename: H
authors.initials: H
authors.lastname: Cho
authors.forename: E
authors.initials: E
authors.lastname: Maldonado
authors.forename: J
authors.initials: J
authors.lastname: Meyer
authors.forename: D
authors.initials: D
authors.lastname: Reinberg
authors.forename: B M
authors.initials: BM
authors.lastname: Peterlin
mesh_terms: D000818:Animals; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D019556:COS Cells; D017931:DNA Primers / Q000235:genetics; D015696:Gene Products, tat / Q000235:genetics / Q000378:metabolism*; D016325:HIV Long Terminal Repeat; D015497:HIV-1 / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D016297:Mutagenesis, Site-Directed; D016133:Polymerase Chain Reaction; D012319:RNA Polymerase II / Q000378:metabolism*; D051381:Rats; D014158:Transcription, Genetic; D054322:tat Gene Products, Human Immunodeficiency Virus
chemical_list: D017931:DNA Primers; D015696:Gene Products, tat; D054322:tat Gene Products, Human Immunodeficiency Virus; D012319:RNA Polymerase II