Year: 2026
Type: article
Abstract: Chromatin organization, through the assembly of DNA with histones and the folding of nucleosome chains, regulates DNA accessibility for transcription, DNA replication and repair. Although models derived from in vitro studies have proposed distinct nucleosome chain geometries, the organization of chromatin within the crowded cell nucleus remains elusive. Using cryo-electron tomography of thin vitreous sections, we directly observed the path of nucleosomal and linker DNA in situ from a flash-frozen organism - Drosophila embryos. We quantified linker length and curvature, characterizing an irregular zig-zag chromatin-folding motif, with a low degree of linker bending. Nucleosome conformations could be identified on individual particles in favorable orientations without structure averaging. Additionally, we observed particles that accommodate a number of DNA gyres ranging from less than one to up to three, which resemble previously proposed non-octameric nucleosomal particles with variable DNA wrapping.
Source: The EMBO Journal
Institutions: Centre National de la Recherche Scientifique, Inserm, Institut de génétique et de biologie moléculaire et cellulaire, Université de Strasbourg, Sorbonne Université, Laboratoire de Physique Théorique de la Matière Condensée, Université Paris-Saclay, Laboratoire de physique des Solides, Goethe University Frankfurt, Thermo Fisher Scientific (Netherlands), European Molecular Biology Laboratory, European Molecular Biology Laboratory, GSI Helmholtz Centre for Heavy Ion Research, Technische Universität Darmstadt
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: gold
Estimated APC paid: $7,990
Awards: Verbundprojekt VERCHROMT II: Erkennung, Verarbeitung und biologische Konsequenzen von Chromatinschäden nach Teilchenbestrahlung II, Teilprojekt A, G265104915, G269015663, Integrated structural analysis of eukaryotic chromatin in situ. Are nucleosome conformation and local order related to chromatin functional state?, G5617488406, G5932539063, G6202389959, Deciphering chromatin rearrangements in response to UV irradiation using new deep learning tools for cryo-electron tomography data analysis, G7047870856, G7240651115, G7889110103
OpenAlex ID: W7128430005