7UIG

Mediator-PIC Early (Mediator A)

This is a non-PDB format compatible entry.

Summary for 7UIG

• Entry DOI: 10.2210/pdb7uig/pdb
• EMDB information: 26545
• Descriptor: Mediator of RNA polymerase II transcription subunit 1, Mediator of RNA polymerase II transcription subunit 17, Mediator of RNA polymerase II transcription subunit 18, ... (17 entities in total)
• Functional Keywords: divergent transcription, mediator, rna polymerase ii, pic, pre-initiation, activation, transcription factor, gal4, gal4vp16, transcription
• Biological source: Saccharomyces cerevisiae (baker's yeast); More
• Total number of polymer chains: 17
• Total formula weight: 749712.24

Authors

Gorbea Colon, J.J.,Chen, S.-F.,Tsai, K.L.,Murakami, K. (deposition date: 2022-03-29, release date: 2023-02-15, Last modification date: 2024-06-12)

Primary citation

Gorbea Colon, J.J.,Palao 3rd, L.,Chen, S.F.,Kim, H.J.,Snyder, L.,Chang, Y.W.,Tsai, K.L.,Murakami, K.
Structural basis of a transcription pre-initiation complex on a divergent promoter.
Mol.Cell, 83:574-, 2023

PubMed 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.

PubMed: 36731470
DOI: 10.1016/j.molcel.2023.01.011

Experimental method

ELECTRON MICROSCOPY (4.3 Å)