title: Linker histones incorporation maintains chromatin fiber plasticity.
abstract: Genomic DNA in eukaryotic cells is organized in supercoiled chromatin fibers, which undergo dynamic changes during such DNA metabolic processes as transcription or replication. Indeed, DNA-translocating enzymes like polymerases produce physical constraints in vivo. We used single-molecule micromanipulation by magnetic tweezers to study the response of chromatin to mechanical constraints in the same range as those encountered in vivo. We had previously shown that under positive torsional constraints, nucleosomes can undergo a reversible chiral transition toward a state of positive topology. We demonstrate here that chromatin fibers comprising linker histones present a torsional plasticity similar to that of naked nucleosome arrays. Chromatosomes can undergo a reversible chiral transition toward a state of positive torsion (reverse chromatosome) without loss of linker histones.
authors.affiliation: Institut Curie, Centre National de la Recherche Scientifique UMR 168, Université Pierre et Marie Curie, Paris, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Recouvreux
authors.forename: Christophe
authors.initials: C
authors.lastname: Lavelle
authors.forename: Maria
authors.initials: M
authors.lastname: Barbi
authors.forename: Natalia
authors.initials: N
authors.lastname: Conde E Silva
authors.forename: Eric
authors.initials: E
authors.lastname: Le Cam
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Victor
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Viovy
mesh_terms: D001696:Biomechanical Phenomena; D002843:Chromatin / Q000737:chemistry / Q000378:metabolism*; D042002:Chromatin Assembly and Disassembly; D006657:Histones / Q000737:chemistry / Q000378:metabolism*; D055595:Mechanical Phenomena; D008958:Models, Molecular; D009707:Nucleosomes / Q000737:chemistry / Q000378:metabolism; D011487:Protein Conformation; D012399:Rotation
chemical_list: D002843:Chromatin; D006657:Histones; D009707:Nucleosomes