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Crystal Structure of a TAF1-TAF7 Complex in Human Transcription Factor IID
Structural highlights
DiseaseTAF1_HUMAN Defects in TAF1 are the cause of dystonia type 3 (DYT3) [MIM:314250; also called X-linked dystonia-parkinsonism (XDP). DYT3 is a X-linked dystonia-parkinsonism disorder. Dystonia is defined by the presence of sustained involuntary muscle contractions, often leading to abnormal postures. DYT3 is characterized by severe progressive torsion dystonia followed by parkinsonism. Its prevalence is high in the Philippines. DYT3 has a well-defined pathology of extensive neuronal loss and mosaic gliosis in the striatum (caudate nucleus and putamen) which appears to resemble that in Huntington disease.[1] [2] FunctionTAF1_HUMAN Largest component and core scaffold of the TFIID basal transcription factor complex. Contains novel N- and C-terminal Ser/Thr kinase domains which can autophosphorylate or transphosphorylate other transcription factors. Phosphorylates TP53 on 'Thr-55' which leads to MDM2-mediated degradation of TP53. Phosphorylates GTF2A1 and GTF2F1 on Ser residues. Possesses DNA-binding activity. Essential for progression of the G1 phase of the cell cycle.[3] [4] [5] [6] [7] [8] [9] Publication Abstract from PubMedThe general transcription factor IID (TFIID) initiates RNA polymerase II-mediated eukaryotic transcription by nucleating pre-initiation complex formation at the core promoter of protein-encoding genes. TAF1, the largest integral subunit of TFIID, contains an evolutionarily conserved yet poorly characterized central core domain, whose specific mutation disrupts cell proliferation in the temperature-sensitive mutant hamster cell line ts13. Although the impaired TAF1 function in the ts13 mutant has been associated with defective transcriptional regulation of cell cycle genes, the mechanism by which TAF1 mediates transcription as part of TFIID remains unclear. Here, we present the crystal structure of the human TAF1 central core domain in complex with another conserved TFIID subunit, TAF7, which biochemically solubilizes TAF1. The TAF1-TAF7 complex displays an inter-digitated compact architecture, featuring an unexpected TAF1 winged helix (WH) domain mounted on top of a heterodimeric triple barrel. The single TAF1 residue altered in the ts13 mutant is buried at the junction of these two structural domains. We show that the TAF1 WH domain has intrinsic DNA-binding activity, which depends on characteristic residues that are commonly used by WH fold proteins for interacting with DNA. Importantly, mutations of these residues not only compromise DNA binding by TAF1, but also abrogate its ability to rescue the ts13 mutant phenotype. Together, our results resolve the structural organization of the TAF1-TAF7 module in TFIID and unveil a critical promoter-binding function of TAF1 in transcription regulation. Crystal structure of a TAF1-TAF7 complex in human transcription factor IID reveals a promoter binding module.,Wang H, Curran EC, Hinds TR, Wang EH, Zheng N Cell Res. 2014 Dec;24(12):1433-44. doi: 10.1038/cr.2014.148. Epub 2014 Nov 21. PMID:25412659[10] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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