title: Structural and functional analyses of nucleosome complexes with mouse histone variants TH2a and TH2b, involved in reprogramming.
abstract: Histone variants TH2a and TH2b are highly expressed in testes, oocytes and zygotes. Our recent analysis suggested that these histone variants enhance the induced generation of pluripotent stem cells (iPSCs) when co-expressed along with four transcription factors, Oct3/4, Sox2, Klf4 and c-Myc (OSKM), and are associated with an open chromatin structure [1]. In the present study, we report the crystal structures of nucleosomes (NCPs) with the mouse histone variants, TH2a and TH2b. The structures revealed two significant changes, as compared to the canonical counterparts: fewer histone-DNA contacts and changes in dimer-dimer interactions between TH2a-TH2a' (L1-loop). In vivo studies with domain swapping and point mutants of the variants revealed that the residues in the histone tails and the TH2a-L1 loop are important for reprogramming. Taken together, our work indicates that the NCP variants with structural modifications and flexible tails are most likely important for enhanced reprogramming of functions.
authors.affiliation: RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan.
authors.forename: Sivaraman
authors.initials: S
authors.lastname: Padavattan
authors.affiliation: Laboratory of Molecular Genetics, CREST Research Project of JST (Japan Science and Technology Agency), RIKEN Tsukuba Institute, 3-1-1 Koyadai, Tsukuba, Ibaraki 305-0074, Japan.
authors.forename: Toshie
authors.initials: T
authors.lastname: Shinagawa
authors.affiliation: Japan Synchrotron Radiation Research Institute (SPring-8), 1-1-1 Kouto, Sayo-cho, Sayo-kun, Hyogo 679-5198, Japan.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Hasegawa
authors.affiliation: Japan Synchrotron Radiation Research Institute (SPring-8), 1-1-1 Kouto, Sayo-cho, Sayo-kun, Hyogo 679-5198, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Kumasaka
authors.affiliation: Laboratory of Molecular Genetics, CREST Research Project of JST (Japan Science and Technology Agency), RIKEN Tsukuba Institute, 3-1-1 Koyadai, Tsukuba, Ibaraki 305-0074, Japan.
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Ishii
authors.affiliation: RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan; Structural Biology Laboratory, RIKEN Yokohama Institute, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, Kanagawa 230-0045, Japan. Electronic address: kumarevel.thirumananseri@riken.jp.
authors.forename: Thirumananseri
authors.initials: T
authors.lastname: Kumarevel
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002478:Cells, Cultured; D065150:Cellular Reprogramming; D018360:Crystallography, X-Ray; D006657:Histones / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D057026:Induced Pluripotent Stem Cells / Q000502:physiology*; D000090062:Kruppel-Like Factor 4; D008297:Male; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009707:Nucleosomes / Q000737:chemistry* / Q000378:metabolism; D017354:Point Mutation; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D013737:Testis / Q000166:cytology
chemical_list: D006657:Histones; C000715467:KLF4 protein, human; C000715468:Klf4 protein, mouse; D000090062:Kruppel-Like Factor 4; D009707:Nucleosomes
keywords: Chromatin; Histone variants; Reprogramming; TH2a; TH2b