title: Gas-phase structure of the histone multimers characterized by ion mobility mass spectrometry and molecular dynamics simulation.
abstract: The minimum structural unit of chromatin is the nucleosome core particle (NCP), consisting of 146 bp of DNA wrapped around a histone octamer, which itself contains two H2A/H2B dimers and one (H3/H4)2 tetramer. These multimers possess functionally important tail regions that are intrinsically disordered. In order to elucidate the mechanisms behind NCP assembly and disassembly processes, which are highly related to gene expression, structural characterization of the H2A/H2B dimer and (H3/H4)2 tetramer will be of importance. In the present study, human histone multimers with disordered tail regions were characterized by electrospray ionization (ESI) ion mobility-mass spectrometry (IM-MS) and molecular dynamics (MD) simulation. Experimentally obtained arrival times of these histone multimer ions showed rather wide distributions, implying that multiple conformers exist for each histone multimer in the gas phase. To examine their structures, MD simulations of the histone multimers were performed first in solution and then in vacuo at four temperatures, resulting in a variety of histone multimer structures. Theoretical collision cross-section (CCS) values calculated for the simulated structures revealed that structural models with smaller CCS values had more compact tail regions than those with larger CCS values. This implied that variation of the CCS values of the histone multimers were primarily due to the random behaviors of the tail regions in the gas phase. The combination of IM-MS and MD simulation enabled clear and comprehensive characterization of the gas-phase structures of histone multimers containing disordered tails.
authors.affiliation: Department of Supramolecular Biology, Graduate School of Nanobioscience, Yokohama City University, 1-7-29 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan.
authors.forename: Kazumi
authors.initials: K
authors.lastname: Saikusa
authors.forename: Sotaro
authors.initials: S
authors.lastname: Fuchigami
authors.forename: Kyohei
authors.initials: K
authors.lastname: Takahashi
authors.forename: Yuuki
authors.initials: Y
authors.lastname: Asano
authors.forename: Aritaka
authors.initials: A
authors.lastname: Nagadoi
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Tachiwana
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Kurumizaka
authors.forename: Mitsunori
authors.initials: M
authors.lastname: Ikeguchi
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Nishimura
authors.forename: Satoko
authors.initials: S
authors.lastname: Akashi
mesh_terms: D042002:Chromatin Assembly and Disassembly; D005740:Gases; D006657:Histones / Q000737:chemistry*; D006801:Humans; D056004:Molecular Dynamics Simulation; D009707:Nucleosomes / Q000737:chemistry*; D011487:Protein Conformation; D020033:Protein Isoforms / Q000737:chemistry; D055503:Protein Multimerization; D058849:Protein Refolding; D011994:Recombinant Proteins / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D005740:Gases; D006657:Histones; D009707:Nucleosomes; D020033:Protein Isoforms; D011994:Recombinant Proteins