DSSR-PyMOL cartoon-block schematics: PDB entry 5iy6

PDB-id

5iy6; DSSR-derived features in text and JSON formats

Class

transcription, transferase-DNA

Method

cryo-EM (7.2 Å)

Summary

Human holo-pic in the closed state

Reference

He Y, Yan C, Fang J, Inouye C, Tjian R, Ivanov I, Nogales E (2016): "Near-atomic resolution visualization of human transcription promoter opening." Nature, 533, 359-365. doi: 10.1038/nature17970.

Abstract

In eukaryotic transcription initiation, a large multi-subunit pre-initiation complex (PIC) that assembles at the core promoter is required for the opening of the duplex DNA and identification of the start site for transcription by RNA polymerase II. Here we use cryo-electron microscropy (cryo-EM) to determine near-atomic resolution structures of the human PIC in a closed state (engaged with duplex DNA), an open state (engaged with a transcription bubble), and an initially transcribing complex (containing six base pairs of DNA-RNA hybrid). Our studies provide structures for previously uncharacterized components of the PIC, such as TFIIE and TFIIH, and segments of TFIIA, TFIIB and TFIIF. Comparison of the different structures reveals the sequential conformational changes that accompany the transition from each state to the next throughout the transcription initiation process. This analysis illustrates the key role of TFIIB in transcription bubble stabilization and provides strong structural support for a translocase activity of XPB.