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Conserved architecture of the core RNA polymerase II initiation complex

2014; Nature Portfolio; Volume: 5; Issue: 1 Linguagem: Inglês

10.1038/ncomms5310

2041-1723

Wolfgang Mühlbacher, Sarah Sainsbury, Matthias Hemann, M. Hantsche, Simon Neyer, Franz Herzog, Patrick Cramer,

RNA and protein synthesis mechanisms

During transcription initiation at promoters of protein-coding genes, RNA polymerase (Pol) II assembles with TBP, TFIIB and TFIIF into a conserved core initiation complex that recruits additional factors. The core complex stabilizes open DNA and initiates RNA synthesis, and it is conserved in the Pol I and Pol III transcription systems. Here, we derive the domain architecture of the yeast core pol II initiation complex during transcription initiation. The yeast complex resembles the human initiation complex and reveals that the TFIIF Tfg2 winged helix domain swings over promoter DNA. An 'arm' and a 'charged helix' in TFIIF function in transcription start site selection and initial RNA synthesis, respectively, and apparently extend into the active centre cleft. Our model provides the basis for further structure–function analysis of the entire transcription initiation complex. It was suggested that despite the conservation of their components, yeast and human pol II initiation complexes diverged in architecture. Mühlbacher et al.now demonstrate that the yeast and human core complexes are structurally conserved and provide insight into the conformations adopted by TFIIF during initiation.