Human CRSP interacts with RNA polymerase II CTD and adopts a specific CTD-bound conformation.
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.
Näär
Anders M
AM
Department of Cell Biology, Harvard Medical School, Massachusetts General Hospital Cancer Center, Charlestown 02129, USA.
Taatjes
Dylan J
DJ
Zhai
Weiguo
W
Nogales
Eva
E
Tjian
Robert
R
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
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