RNA polymerase II/TFIIF structure and conserved organization of the initiation complex.
The structure of an RNA polymerase II/general transcription factor TFIIF complex was determined by cryo-electron microscopy and single particle analysis. Density due to TFIIF was not concentrated in one area but rather was widely distributed across the surface of the polymerase. The largest subunit of TFIIF interacted with the dissociable Rpb4/Rpb7 polymerase subunit complex and with the mobile "clamp." The distribution of the second largest subunit of TFIIF was very similar to that previously reported for the sigma subunit in the bacterial RNA polymerase holoenzyme, consisting of a series of globular domains extending along the polymerase active site cleft. This result indicates that the second TFIIF subunit is a true structural homolog of the bacterial sigma factor and reveals an important similarity of the transcription initiation mechanism between bacteria and eukaryotes. The structure of the RNAPII/TFIIF complex suggests a model for the organization of a minimal transcription initiation complex.
Department of Cell Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
Wen-Hsiang
WH
Chung
John L
JL
Craighead
Wei-Hau
WH
Chang
Chukwudi
C
Ezeokonkwo
Avital
A
Bareket-Samish
Roger D
RD
Kornberg
Francisco J
FJ
Asturias
D000818:Animals; D019143:Evolution, Molecular; D006801:Humans; D046911:Macromolecular Substances; D008854:Microscopy, Electron; D008958:Models, Molecular; D015394:Molecular Structure; D010802:Phylogeny; D011401:Promoter Regions, Genetic / Q000502:physiology; D021122:Protein Subunits / Q000737:chemistry; D012319:RNA Polymerase II / Q000737:chemistry* / Q000648:ultrastructure*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000648:ultrastructure; D019473:Transcription Factors, TFII / Q000737:chemistry* / Q000648:ultrastructure*; D024363:Transcription Initiation Site / Q000502:physiology*; D015003:Yeasts
D046911:Macromolecular Substances; D021122:Protein Subunits; D029701:Saccharomyces cerevisiae Proteins; D019473:Transcription Factors, TFII; D012319:RNA Polymerase II; C423309:RPB4 protein, S cerevisiae; C470553:RPB7 protein, S cerevisiae; C056604:transcription factor TFIIF