Download MendeleyStructural basis of a transcription pre-initiation complex on a divergent promoter.
Gorbea Colon, J.J., Palao 3rd, L., Chen, S.F., Kim, H.J., Snyder, L., Chang, Y.W., Tsai, K.L., Murakami, K.(2023) Mol Cell 83: 574
- PubMed: 36731470
- DOI: https://doi.org/10.1016/j.molcel.2023.01.011
- Primary Citation of Related Structures:
7UI9, 7UIC, 7UIF, 7UIG, 7UIK, 7UIL, 7UIO - 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.
Organizational Affiliation:
Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
