title: Histone H3.5 forms an unstable nucleosome and accumulates around transcription start sites in human testis.
abstract: BACKGROUND
  Human histone H3.5 is a non-allelic H3 variant evolutionally derived from H3.3. The H3.5 mRNA is highly expressed in human testis. However, the function of H3.5 has remained poorly understood.
  
  
  RESULTS
  We found that the H3.5 nucleosome is less stable than the H3.3 nucleosome. The crystal structure of the H3.5 nucleosome showed that the H3.5-specific Leu103 residue, which corresponds to the H3.3 Phe104 residue, reduces the hydrophobic interaction with histone H4. Mutational analyses revealed that the H3.5-specific Leu103 residue is responsible for the instability of the H3.5 nucleosome, both in vitro and in living cells. The H3.5 protein was present in human seminiferous tubules, but little to none was found in mature sperm. A chromatin immunoprecipitation coupled with sequencing analysis revealed that H3.5 accumulated around transcription start sites (TSSs) in testicular cells.
  
  
  CONCLUSIONS
  We performed comprehensive studies of H3.5, and found the instability of the H3.5 nucleosome and the accumulation of H3.5 protein around TSSs in human testis. The unstable H3.5 nucleosome may function in the chromatin dynamics around the TSSs, during spermatogenesis.
authors.affiliation: Laboratory of Structural Biology, Graduate School of Advanced Science and Engineering, Institute for Medical-oriented Structural Biology, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo, 162-8480 Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Urahama
authors.affiliation: Division of Transcriptomics, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, Fukuoka 812-8582 Japan.
authors.forename: Akihito
authors.initials: A
authors.lastname: Harada
authors.affiliation: Division of Transcriptomics, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, Fukuoka 812-8582 Japan.
authors.forename: Kazumitsu
authors.initials: K
authors.lastname: Maehara
authors.affiliation: Laboratory of Structural Biology, Graduate School of Advanced Science and Engineering, Institute for Medical-oriented Structural Biology, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo, 162-8480 Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Horikoshi
authors.affiliation: Laboratory of Structural Biology, Graduate School of Advanced Science and Engineering, Institute for Medical-oriented Structural Biology, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo, 162-8480 Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Sato
authors.affiliation: Department of Biological Sciences, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, 226-8501 Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Sato
authors.affiliation: Faculty of Medicine and Health Sciences, Yamaguchi University, 1-1-1 Minami-Kogushi, Ube, 755-8505 Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Shiraishi
authors.affiliation: Faculty of Medicine and Health Sciences, Yamaguchi University, 1-1-1 Minami-Kogushi, Ube, 755-8505 Japan.
authors.forename: Norihiro
authors.initials: N
authors.lastname: Sugino
authors.affiliation: Laboratory of Structural Biology, Graduate School of Advanced Science and Engineering, Institute for Medical-oriented Structural Biology, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo, 162-8480 Japan.
authors.forename: Akihisa
authors.initials: A
authors.lastname: Osakabe
authors.affiliation: Laboratory of Structural Biology, Graduate School of Advanced Science and Engineering, Institute for Medical-oriented Structural Biology, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo, 162-8480 Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Tachiwana
authors.affiliation: Program in Chemistry and Life Science, School of Science and Engineering, Meisei University, 2-1-1 Hodokubo, Hino, Tokyo 191-8506 Japan.
authors.forename: Wataru
authors.initials: W
authors.lastname: Kagawa
authors.affiliation: Department of Biological Sciences, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, 226-8501 Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kimura
authors.affiliation: Division of Transcriptomics, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, Fukuoka 812-8582 Japan.
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Ohkawa
authors.affiliation: Laboratory of Structural Biology, Graduate School of Advanced Science and Engineering, Institute for Medical-oriented Structural Biology, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo, 162-8480 Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Kurumizaka
keywords: Chromatin; Histone variant; Nucleosome; Spermatogenesis; Testis; Transcription start site