title: A distinct switch in interactions of the histone H4 tail domain upon salt-dependent folding of nucleosome arrays.
abstract: The core histone tail domains mediate inter-nucleosomal interactions that direct folding and condensation of nucleosome arrays into higher-order chromatin structures. The histone H4 tail domain facilitates inter-array interactions by contacting both the H2A/H2B acidic patch and DNA of neighboring nucleosomes. Likewise, H4 tail-H2A contacts stabilize array folding. However, whether the H4 tail domains stabilize array folding via inter-nucleosomal interactions with the DNA of neighboring nucleosomes remains unclear. We utilized defined oligonucleosome arrays containing a single specialized nucleosome with a photo-inducible cross-linker in the N terminus of the H4 tail to characterize these interactions. We observed that the H4 tail participates exclusively in intra-array interactions with DNA in unfolded arrays. These interactions are diminished during array folding, yet no inter-nucleosome, intra-array H4 tail-DNA contacts are observed in condensed chromatin. However, we document contacts between the N terminus of the H4 tail and H2A. Installation of acetylation mimics known to disrupt H4-H2A surface interactions did not increase observance of H4-DNA inter-nucleosomal interactions. These results suggest the multiple functions of the H4 tail require targeted distinct interactions within condensed chromatin.
authors.affiliation: Department of Biochemistry and Biophysics, University of Rochester, Rochester, New York 14642.
authors.forename: Sharon
authors.initials: S
authors.lastname: Pepenella
authors.affiliation: Department of Biochemistry and Biophysics, University of Rochester, Rochester, New York 14642.
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Murphy
authors.affiliation: Department of Biochemistry and Biophysics, University of Rochester, Rochester, New York 14642. Electronic address: Jeffrey_Hayes@urmc.rochester.edu.
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Hayes
mesh_terms: D000107:Acetylation; D000818:Animals; D004247:DNA / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006657:Histones / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009707:Nucleosomes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017510:Protein Folding; D055550:Protein Stability; D017434:Protein Structure, Tertiary; D014981:Xenopus; D029867:Xenopus Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D006657:Histones; D009707:Nucleosomes; D029867:Xenopus Proteins; D004247:DNA
keywords: Chromatin; Chromatin Regulation; Chromatin Structure; Higher-order Chromatin Structure; Histone; Histone Tail Domain; Nucleosome