title: Human CRSP interacts with RNA polymerase II CTD and adopts a specific CTD-bound conformation.
abstract: Activation of gene transcription in mammalian cells requires several classes of coactivators that participate in different steps of the activation cascade. Using conventional and affinity chromatography, we have isolated a human coactivator complex that interacts directly with the C-terminal domain (CTD) of RNA polymerase II (Pol II). The CTD-binding complex is structurally and functionally indistinguishable from our previously isolated CRSP coactivator complex. The closely related, but transcriptionally inactive, ARC-L complex failed to interact with the CTD, indicating a significant biochemical difference between CRSP and ARC-L that may, in part, explain their functional divergence. Electron microscopy and three-dimensional single-particle reconstruction reveals a conformation for CTD-CRSP that is structurally distinct from unliganded CRSP or CRSP bound to SREBP-1a, but highly similar to CRSP bound to the VP16 activator. Together, our findings suggest that the human CRSP coactivator functions, at least in part, by mediating activator-dependent recruitment of RNA Pol II via the CTD.
authors.affiliation: Department of Cell Biology, Harvard Medical School, Massachusetts General Hospital Cancer Center, Charlestown 02129, USA.
authors.forename: Anders M
authors.initials: AM
authors.lastname: Näär
authors.forename: Dylan J
authors.initials: DJ
authors.lastname: Taatjes
authors.forename: Weiguo
authors.initials: W
authors.lastname: Zhai
authors.forename: Eva
authors.initials: E
authors.lastname: Nogales
authors.forename: Robert
authors.initials: R
authors.lastname: Tjian
mesh_terms: D001665:Binding Sites; D002843:Chromatin / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D005982:Glutathione Transferase / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D015151:Immunoblotting; D008024:Ligands; D056892:Mediator Complex; D008854:Microscopy, Electron; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D012319:RNA Polymerase II / Q000737:chemistry*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015534:Trans-Activators / Q000737:chemistry* / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: C117286:CRSP protein, human; D002843:Chromatin; D008024:Ligands; C492155:MED26 protein, human; D056892:Mediator Complex; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators; D005982:Glutathione Transferase; D012319:RNA Polymerase II