Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.10.10.334474v1?rss=1 Authors: Rudnizky, S., Khamis, H., Ginosar, Y., Goren, E., Melamed, P., Kaplan, A. Abstract: Chromatosomes, composed of nucleosomes and linker histones, play a fundamental role in chromatin regulation. However, a detailed understanding of their structure is lacking, partially due to their complex dynamics. Using single-molecule DNA unzipping with optical tweezers to map histone-DNA interactions in the chromatosome, we reveal a symmetrical compaction of the nucleosome core, governed by the linker histone globular domain contacts at the dyad. Dynamic mapping revealed that the C-terminal domain binds both DNA linkers, at ~ {+/-}115 and ~ {+/-}140 bp from the dyad, to compact the nucleosome entry and exit. Although H1 interacts more transiently with one linker, these dynamic contacts are crucial for stabilizing the binding to the second one. Extensive unzipping of the linker DNA, which mimics its invasion by motor proteins, shifts H1 off the dyad, triggering nucleosome decompaction. Our findings reveal molecular details of chromatosome compaction and its potential modulation by the transcription machinery. Copy rights belong to original authors. Visit the link for more info