title: Chromatin structure-dependent conformations of the H1 CTD.
abstract: Linker histones are an integral component of chromatin but how these proteins promote assembly of chromatin fibers and higher order structures and regulate gene expression remains an open question. Using Förster resonance energy transfer (FRET) approaches we find that association of a linker histone with oligonucleosomal arrays induces condensation of the intrinsically disordered H1 CTD in a manner consistent with adoption of a defined fold or ensemble of folds in the bound state. However, H1 CTD structure when bound to nucleosomes in arrays is distinct from that induced upon H1 association with mononucleosomes or bare double stranded DNA. Moreover, the H1 CTD becomes more condensed upon condensation of extended nucleosome arrays to the contacting zig-zag form found in moderate salts, but does not detectably change during folding to fully compacted chromatin fibers. We provide evidence that linker DNA conformation is a key determinant of H1 CTD structure and that constraints imposed by neighboring nucleosomes cause linker DNAs to adopt distinct trajectories in oligonucleosomes compared to H1-bound mononucleosomes. Finally, inter-molecular FRET between H1s within fully condensed nucleosome arrays suggests a regular spatial arrangement for the H1 CTD within the 30 nm chromatin fiber.
authors.affiliation: Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, NY 14642, USA.
authors.forename: He
authors.initials: H
authors.lastname: Fang
authors.affiliation: Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA.
authors.forename: Sijie
authors.initials: S
authors.lastname: Wei
authors.affiliation: Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA.
authors.forename: Tae-Hee
authors.initials: TH
authors.lastname: Lee
authors.affiliation: Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, NY 14642, USA Jeffrey_Hayes@urmc.rochester.edu.
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Hayes
mesh_terms: D000818:Animals; D002843:Chromatin / Q000737:chemistry* / Q000378:metabolism; D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D031541:Fluorescence Resonance Energy Transfer; D006657:Histones / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D009690:Nucleic Acid Conformation; D009707:Nucleosomes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism
chemical_list: D002843:Chromatin; D006657:Histones; D009707:Nucleosomes; D011994:Recombinant Proteins; D004247:DNA