EMD-31213

Single-particle
7.1 Å
EMD-31213 Deposition: 17/04/2021
Map released: 19/05/2021
Last modified: 19/05/2021
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links

EMD-31213

Human Mediator in a Tail-bent conformation (MED-B)

EMD-31213

Single-particle
7.1 Å
EMD-31213 Deposition: 17/04/2021
Map released: 19/05/2021
Last modified: 19/05/2021
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Sample Organism: Homo sapiens
Sample: Structure of the human Mediator complex

Deposition Authors: Yin X, Li J, Wu Z, Liu W, Xu Y
Structures of the human Mediator and Mediator-bound preinitiation complex.
Chen X , Yin X , Li J , Wu Z , Qi Y , Wang X , Liu W , Xu Y
(2021) Science
PUBMED: 33958484
DOI: doi:10.1126/science.abg0635
ISSN: 1095-9203
ASTM: SCIEAS
Abstract:
The 1.3-megadalton transcription factor IID (TFIID) is required for preinitiation complex (PIC) assembly and RNA polymerase II (Pol II)-mediated transcription initiation on almost all genes. The 26-subunit Mediator stimulates transcription and cyclin-dependent kinase 7 (CDK7)-mediated phosphorylation of the Pol II C-terminal domain (CTD). We determined the structures of human Mediator in the Tail module-extended (at near-atomic resolution) and Tail-bent conformations and structures of TFIID-based PIC-Mediator (76 polypeptides, ~4.1 megadaltons) in four distinct conformations. PIC-Mediator assembly induces concerted reorganization (Head-tilting and Middle-down) of Mediator and creates a Head-Middle sandwich, which stabilizes two CTD segments and brings CTD to CDK7 for phosphorylation; this suggests a CTD-gating mechanism favorable for phosphorylation. The TFIID-based PIC architecture modulates Mediator organization and TFIIH stabilization, underscoring the importance of TFIID in orchestrating PIC-Mediator assembly.