IWS1 positions downstream DNA to globally stimulate Pol II elongation.

The protein IWS1 (Interacts with SPT6 1) is implicated in transcription-associated processes, but a direct role in RNA polymerase (Pol) II function is unknown. Here, we use multi-omics kinetic analysis after rapid depletion of IWS1 in human cells to show that loss of IWS1 results in a global decrease of RNA synthesis and a global reduction in Pol II elongation velocity. We then resolve the cryo-EM structure of the activated Pol II elongation complex with bound IWS1 and elongation factor ELOF1 and show that IWS1 acts as a scaffold and positions downstream DNA within the cleft of Pol II.

FACT maintains chromatin architecture and thereby stimulates RNA polymerase II pausing during transcription in vivo.

Facilitates chromatin transcription (FACT) is a histone chaperone that supports transcription through chromatin in vitro, but its functional roles in vivo remain unclear. Here, we analyze the in vivo functions of FACT with the use of multi-omics analysis after rapid FACT depletion from human cells. We show that FACT depletion destabilizes chromatin and leads to transcriptional defects, including defective promoter-proximal pausing and elongation, and increased premature termination of RNA polymerase II.

Structural basis of Integrator-dependent RNA polymerase II termination.

The Integrator complex can terminate RNA polymerase II (Pol II) in the promoter-proximal region of genes. Previous work has shed light on how Integrator binds to the paused elongation complex consisting of Pol II, the DRB sensitivity-inducing factor (DSIF) and the negative elongation factor (NELF) and how it cleaves the nascent RNA transcript, but has not explained how Integrator removes Pol II from the DNA template. Here we present three cryo-electron microscopy structures of the complete Integrator-PP2A complex in different functional states.

Structure of a backtracked hexasomal intermediate of nucleosome transcription.

During gene transcription, RNA polymerase II (RNA Pol II) passes nucleosomes with the help of various elongation factors. Here, we show that RNA Pol II achieves efficient nucleosome passage when the human elongation factors DSIF, PAF1 complex (PAF), RTF1, SPT6, and TFIIS are present. The cryo-EM structure of an intermediate of the nucleosome passage shows a partially unraveled hexasome that lacks the proximal H2A-H2B dimer and interacts with the RNA Pol II jaw, DSIF, and the CTR9trestle helix.

Structural basis of nucleosome transcription mediated by Chd1 and FACT.

Efficient transcription of RNA polymerase II (Pol II) through nucleosomes requires the help of various factors. Here we show biochemically that Pol II transcription through a nucleosome is facilitated by the chromatin remodeler Chd1 and the histone chaperone FACT when the elongation factors Spt4/5 and TFIIS are present. We report cryo-EM structures of transcribing Saccharomyces cerevisiae Pol II-Spt4/5-nucleosome complexes with bound Chd1 or FACT.

Nucleosome-CHD4 chromatin remodeler structure maps human disease mutations.

Chromatin remodeling plays important roles in gene regulation during development, differentiation and in disease. The chromatin remodeling enzyme CHD4 is a component of the NuRD and ChAHP complexes that are involved in gene repression. Here, we report the cryo-electron microscopy (cryo-EM) structure of CHD4 engaged with a nucleosome core particle in the presence of the non-hydrolysable ATP analogue AMP-PNP at an overall resolution of 3.