title: Association of an activator with an RNA polymerase II holoenzyme.
abstract: RNA polymerase II holoenzymes have been described that consist of RNA polymerase II, a subset of general transcription factors, and four SRB proteins. The SRB proteins, which were identified through a selection for genes involved in transcription initiation by RNA polymerase II in vivo, are a hallmark of the holoenzyme. We report here the isolation and characterization of additional SRB genes. We show that the products of all nine SRB genes identified thus far are components of the RNA polymerase II holoenzyme and are associated with a holoenzyme subcomplex termed the mediator of activation. The holoenzyme is capable of responding to a transcriptional activator, suggesting a model in which activators function, in part, through direct interactions with the holoenzyme. Immunoprecipitation experiments with anti-SRB5 antibodies demonstrate that the acidic activating domain of VP16 specifically binds to the holoenzyme. Furthermore, the holoenzyme and the mediator subcomplex bind to a VP16 affinity column. These results provide a more complete description of the RNA polymerase II holoenzyme and suggest that this form of the transcription apparatus can be recruited to promoters via direct interactions with activators.
authors.affiliation: Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142, USA.
authors.forename: C J
authors.initials: CJ
authors.lastname: Hengartner
authors.forename: C M
authors.initials: CM
authors.lastname: Thompson
authors.forename: J
authors.initials: J
authors.lastname: Zhang
authors.forename: D M
authors.initials: DM
authors.lastname: Chao
authors.forename: S M
authors.initials: SM
authors.lastname: Liao
authors.forename: A J
authors.initials: AJ
authors.lastname: Koleske
authors.forename: S
authors.initials: S
authors.lastname: Okamura
authors.forename: R A
authors.initials: RA
authors.lastname: Young
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D005800:Genes, Fungal / Q000235:genetics*; D017405:Herpes Simplex Virus Protein Vmw65 / Q000378:metabolism; D046911:Macromolecular Substances; D056892:Mediator Complex; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation; D011233:Precipitin Tests; D011485:Protein Binding; D012319:RNA Polymerase II / Q000235:genetics* / Q000378:metabolism; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D017422:Sequence Analysis, DNA; D013489:Suppression, Genetic; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D017405:Herpes Simplex Virus Protein Vmw65; D046911:Macromolecular Substances; D056892:Mediator Complex; C093965:SRB7 protein, S cerevisiae; C093967:SSN2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D012319:RNA Polymerase II