NDF/GLYR1 Promotes RNA Polymerase II Processivity via Pol II Binding and Nucleosome Destabilization

The Nucleosome Destabilizing Factor (NDF) facilitates transcription through chromatin, but its precise mechanism remains incompletely understood. Here, we identify a critical region (amino acids 140-160) within NDF that specifically interacts with phosphorylated RPB1, the largest subunit of elongating RNA Polymerase II (Pol II). Mutations in this region disrupt Pol II interaction and impair Pol II elongation both in vitro and in cells, yet do not affect NDF's ability to destabilize nucleosomes, establishing a functional separation between these two activities. Cellular studies reveal that NDF knockout cells display faster Pol II elongation rates but produce fewer nascent transcripts, demonstrating NDF's primary role in maintaining transcriptional processivity throughout gene bodies. Our findings demonstrate that NDF uses distinct mechanisms to ensure productive transcription elongation rather than simply enhancing elongation speed, offering new insights into how transcription efficiency is maintained in chromatin.