7ui9 | pdb_00007ui9
Core Mediator-PICearly (Copy A)
Structural highlights
FunctionT2FA_YEAST TFIIF is a general transcription initiation factor that binds to RNA polymerase II. Its functions include the recruitment of RNA polymerase II to the promoter bound DNA-TBP-TFIIB complex, decreasing the affinity of RNA polymerase II for non-specific DNA, allowing for the subsequent recruitment of TFIIE and TFIIH, and facilitating RNA polymerase II elongation.[1] Publication Abstract from PubMedMost 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 approximately 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. Structural basis of a transcription pre-initiation complex on a divergent promoter.,Gorbea Colon JJ, Palao L 3rd, Chen SF, Kim HJ, Snyder L, Chang YW, Tsai KL, Murakami K Mol Cell. 2023 Jan 26:S1097-2765(23)00031-X. doi: 10.1016/j.molcel.2023.01.011. PMID:36731470[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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