title: Structure, function, and activator-induced conformations of the CRSP coactivator.
abstract: The human cofactor complexes ARC (activator-recruited cofactor) and CRSP (cofactor required for Sp1 activation) mediate activator-dependent transcription in vitro. Although these complexes share several common subunits, their structural and functional relationships remain unknown. Here, we report that affinity-purified ARC consists of two distinct multisubunit complexes: a larger complex, denoted ARC-L, and a smaller coactivator, CRSP. Reconstituted in vitro transcription with biochemically separated ARC-L and CRSP reveals differential cofactor functions. The ARC-L complex is transcriptionally inactive, whereas the CRSP complex is highly active. Structural determination by electron microscopy (EM) and three-dimensional reconstruction indicate substantial differences in size and shape between ARC-L and CRSP. Moreover, EM analysis of independently derived CRSP complexes reveals distinct conformations induced by different activators. These results suggest that CRSP may potentiate transcription via specific activator-induced conformational changes.
authors.affiliation: Howard Hughes Medical Institute and, Lawrence Berkeley National Laboratory, Department of Molecular and Cell Biology, 401 Barker Hall, University of California, Berkeley, CA 94720, USA.
authors.forename: Dylan J
authors.initials: DJ
authors.lastname: Taatjes
authors.forename: Anders M
authors.initials: AM
authors.lastname: Näär
authors.forename: Frank
authors.initials: F
authors.lastname: Andel
authors.forename: Eva
authors.initials: E
authors.lastname: Nogales
authors.forename: Robert
authors.initials: R
authors.lastname: Tjian
mesh_terms: D022762:CCAAT-Enhancer-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D002843:Chromatin / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D006367:HeLa Cells; D017405:Herpes Simplex Virus Protein Vmw65 / Q000378:metabolism; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D046911:Macromolecular Substances; D008854:Microscopy, Electron; D008957:Models, Genetic; D011233:Precipitin Tests; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D021122:Protein Subunits; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D051780:Sterol Regulatory Element Binding Protein 1; D015534:Trans-Activators / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D015533:Transcriptional Activation
chemical_list: D022762:CCAAT-Enhancer-Binding Proteins; C117286:CRSP protein, human; D002843:Chromatin; D004268:DNA-Binding Proteins; D017405:Herpes Simplex Virus Protein Vmw65; D046911:Macromolecular Substances; D021122:Protein Subunits; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; C497387:SREBF1 protein, human; D051780:Sterol Regulatory Element Binding Protein 1; D015534:Trans-Activators; D014157:Transcription Factors