Assignment of structural transitions during mechanical unwrapping of nucleosomes and their disassembly products.

ABSTRACT: Nucleosome DNA unwrapping and its disassembly into hexasomes and tetrasomes is necessary for genomic access and plays an important role in transcription regulation. Previous single-molecule mechanical nucleosome unwrapping revealed a low- and a high-force transitions, and force-FRET pulling experiments showed that DNA unwrapping is asymmetric, occurring always first from one side before the other. However, the assignment of DNA segments involved in these transitions remains controversial. Here, using high-resolution optical tweezers with simultaneous single-molecule FRET detection, we show that the low-force transition corresponds to the undoing of the outer wrap of one side of the nucleosome (∼27 bp), a process that can occur either cooperatively or noncooperatively, whereas the high-forc

SUBMITTER: Diaz-Celis C 

PROVIDER: S-EPMC9388122 | biostudies-literature | 2022 Aug

REPOSITORIES: biostudies-literature