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The structure of a virus-encoded nucleosome

ABSTRACT: Eukaryotes and prokaryotes encode proteins with the histone-fold domain, but only eukaryotes are known to encode "core histones" from four distinct families that heterodimerize selectively and uniquely to form nucleosome particles. Some large DNA viruses, including those in Marseilleviridae family encode histones. The presence of histone proteins in viral particles suggests their role in compacting viral genomes but it is not known whether these histones can form higher-order structures like those found in eukaryotes. Here we show that fused histone pairs Hβ-Hα and Hδ-Hγ from Marseillevirus are structurally analogous to the eukaryotic histone pairs H2B-H2A and H3-H4. We further show that they form “forced” heterodimers and that a heterotetramer of four such heterodimers assembles DNA to form structures virtually identical to those of canonical eukaryotic nucleosomes. We characterize these viral structures using cryo-EM to reveal their unprecedented conservation with the nucleosome—one of the most important and conserved features of eukaryotic chromosomes. The structure and properties of these viral nucleosomes hold clues to understanding the origins of eukaryotic chromatin.

INSTRUMENT(S): Orbitrap Fusion Lumos

ORGANISM(S): Marseillevirus

SUBMITTER: Nikita Vasilyev

LAB HEAD: Evgeny Nudler

PROVIDER: PXD024220 | Pride | 2021-05-27

REPOSITORIES: Pride

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The structure of a virus-encoded nucleosome.

Valencia-Sánchez Marco Igor MI Abini-Agbomson Stephen S Wang Miao M Lee Rachel R Vasilyev Nikita N Zhang Jenny J De Ioannes Pablo P La Scola Bernard B Talbert Paul P Henikoff Steve S Nudler Evgeny E Erives Albert A Armache Karim-Jean KJ

Nature structural & molecular biology 20210429 5

Certain large DNA viruses, including those in the Marseilleviridae family, encode histones. Here we show that fused histone pairs Hβ-Hα and Hδ-Hγ from Marseillevirus are structurally analogous to the eukaryotic histone pairs H2B-H2A and H4-H3. These viral histones form 'forced' heterodimers, and a heterotetramer of four such heterodimers assembles DNA to form structures virtually identical to canonical eukaryotic nucleosomes. ...[more]

PMID: 33927388

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Project description:This model is described in the article: Kinetics of histone gene expression during early development of Xenopus laevis. Koster JG, Destrée OH and Westerhoff HV. J Theor Biol. 1988 Nov 21;135(2):139-67. PMID: 3267765 Abstract: Using literature data for transcriptional and translational rate constants, gene copy numbers, DNA concentrations, and stability constants, we have calculated the expected concentrations of histones and histone mRNA during embryogenesis of Xenopus laevis. The results led us to conclude that: (i) for X. laevis the gene copy number of the histone genes is too low to ensure the synthesis of sufficient histones during very early development, inheritance from the oocyte of either histone protein or histone mRNA (but not necessarily both) is necessary; (ii) from the known storage of histones in the oocyte and the rates of histone synthesis determined by Adamson and Woodland (1977), there would be sufficient histones to structure the newly synthesized DNA up to gastrulation but not thereafter (these empirical rates of histone synthesis may be underestimates); (iii) on the other hand, the amount of H3 mRNA recently observed during early embryogenesis (Koster, 1987, Koster et al., 1988) could direct a higher and sufficient synthesis of H3 protein, also after gastrulation. We present a quantitative model that accounts both for the observed H3 mRNA concentration as a function of time during embryogenesis and for the synthesis of sufficient histones to structure the DNA throughout early embryogenesis. The model suggests that X. laevis exhibits a major (i.e. some 14-fold) reduction in transcription of histone genes approximately 11 hours after fertilization. This reduction could be due to a decrease in the number of transcribed histone genes, a decreased rate constant of transcription with continued transcription of all the histone genes, and/or a reduction in the time during the cell cycle in which histone mRNA synthesis takes place. Alternatively, the histone mRNA stability might decrease approximately 16-fold 11 hours after fertilization. This model originates from BioModels Database: A Database of Annotated Published Models. It is copyright (c) 2005-2011 The BioModels.net Team. To the extent possible under law, all copyright and related or neighbouring rights to this encoded model have been dedicated to the public domain worldwide. Please refer to CC0 Public Domain Dedication for more information. In summary, you are entitled to use this encoded model in absolutely any manner you deem suitable, verbatim, or with modification, alone or embedded it in a larger context, redistribute it, commercially or not, in a restricted way or not.. To cite BioModels Database, please use: Li C, Donizelli M, Rodriguez N, Dharuri H, Endler L, Chelliah V, Li L, He E, Henry A, Stefan MI, Snoep JL, Hucka M, Le Novère N, Laibe C (2010) BioModels Database: An enhanced, curated and annotated resource for published quantitative kinetic models. BMC Syst Biol., 4:92.

Dataset Information

The structure of a virus-encoded nucleosome

Publications

The structure of a virus-encoded nucleosome.

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