More pieces to the puzzle: recent structural insights into class II transcription initiation.
Class II transcription initiation is a highly regulated process and requires the assembly of a pre-initiation complex (PIC) containing DNA template, RNA polymerase II (RNAPII), general transcription factors (GTFs) TFIIA, TFIIB, TFIID, TFIIE, TFIIF, TFIIH and Mediator. RNAPII, TFIID, TFIIH and Mediator are large multiprotein complexes, each containing 10 and more subunits. Altogether, the PIC is made up of about 60 polypeptides with a combined molecular weight of close to 4MDa. Recent structural studies of key PIC components have significantly advanced our understanding of transcription initiation. TFIID was shown to bind promoter DNA in a reorganized state. The architecture of a core-TFIID complex was elucidated. Crystal structures of the TATA-binding protein (TBP) bound to TBP-associated factor 1 (TAF1), RNAPII-TFIIB complexes and the Mediator head module were solved. The overall architectures of large PIC assemblies from human and yeast have been determined by electron microscopy (EM). Here we review these latest structural insights into the architecture and assembly of the PIC, which reveal exciting new mechanistic details of transcription initiation.
European Molecular Biology Laboratory, Grenoble Outstation, 6 rue Jules Horowitz, 38042 Grenoble, France; Unit of Virus Host-Cell Interactions, Unité Mixte Internationale UMI 3265, Université de Grenoble Alpes - EMBL - CNRS, 6 Rue Jules Horowitz, BP181, 38042 Grenoble Cedex 9, France.
Eaazhisai
E
Kandiah
European Molecular Biology Laboratory, Grenoble Outstation, 6 rue Jules Horowitz, 38042 Grenoble, France; Unit of Virus Host-Cell Interactions, Unité Mixte Internationale UMI 3265, Université de Grenoble Alpes - EMBL - CNRS, 6 Rue Jules Horowitz, BP181, 38042 Grenoble Cedex 9, France.
Simon
S
Trowitzsch
European Molecular Biology Laboratory, Grenoble Outstation, 6 rue Jules Horowitz, 38042 Grenoble, France; Unit of Virus Host-Cell Interactions, Unité Mixte Internationale UMI 3265, Université de Grenoble Alpes - EMBL - CNRS, 6 Rue Jules Horowitz, BP181, 38042 Grenoble Cedex 9, France.
Kapil
K
Gupta
European Molecular Biology Laboratory, Grenoble Outstation, 6 rue Jules Horowitz, 38042 Grenoble, France; Unit of Virus Host-Cell Interactions, Unité Mixte Internationale UMI 3265, Université de Grenoble Alpes - EMBL - CNRS, 6 Rue Jules Horowitz, BP181, 38042 Grenoble Cedex 9, France.
Matthias
M
Haffke
European Molecular Biology Laboratory, Grenoble Outstation, 6 rue Jules Horowitz, 38042 Grenoble, France; Unit of Virus Host-Cell Interactions, Unité Mixte Internationale UMI 3265, Université de Grenoble Alpes - EMBL - CNRS, 6 Rue Jules Horowitz, BP181, 38042 Grenoble Cedex 9, France. Electronic address: iberger@embl.fr.
Imre
I
Berger
D000818:Animals; D006801:Humans; D056892:Mediator Complex / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D011487:Protein Conformation; D012319:RNA Polymerase II / Q000737:chemistry / Q000378:metabolism*; D035165:Transcription Factors, General / Q000737:chemistry / Q000378:metabolism*; D015533:Transcriptional Activation
D056892:Mediator Complex; D035165:Transcription Factors, General; D012319:RNA Polymerase II