EMD-26542

Single-particle
3.3 Å
EMD-26542 Deposition: 28/03/2022
Map released: 15/02/2023
Last modified: 23/10/2024
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links

EMD-26542

Core Mediator-PICearly (Copy A)

EMD-26542

Single-particle
3.3 Å
EMD-26542 Deposition: 28/03/2022
Map released: 15/02/2023
Last modified: 23/10/2024
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Sample Organism: Saccharomyces cerevisiae S288C
Sample: Core Mediator-PICearly (Copy A)
Fitted models: 7ui9 (Avg. Q-score: 0.294)

Deposition Authors: Gorbea Colon JJ, Chen S-F, Tsai KL , Murakami K
Structural basis of a transcription pre-initiation complex on a divergent promoter.
PUBMED: 36731470
DOI: doi:10.1016/j.molcel.2023.01.011
ISSN: 1097-2765
ASTM: MOCEFL
Abstract:
Most eukaryotic promoter regions are divergently transcribed. As the RNA polymerase II pre-initiation complex (PIC) is intrinsically asymmetric and responsible for transcription in a single direction, it is unknown how divergent transcription arises. Here, the Saccharomyces cerevisiae Mediator complexed with a PIC (Med-PIC) was assembled on a divergent promoter and analyzed by cryoelectron microscopy. The structure reveals two distinct Med-PICs forming a dimer through the Mediator tail module, induced by a homodimeric activator protein localized near the dimerization interface. The tail dimer is associated with ∼80-bp upstream DNA, such that two flanking core promoter regions are positioned and oriented in a suitable form for PIC assembly in opposite directions. Also, cryoelectron tomography visualized the progress of the PIC assembly on the two core promoter regions, providing direct evidence for the role of the Med-PIC dimer in divergent transcription.