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  • The EMBO Journal (2006) 25, 4234 - 4244
  • doi:10.1038/sj.emboj.7601310

Published online: 7 September 2006

Dissection of the unusual structural and functional properties of the variant H2A.Bbd nucleosome

Cécile-Marie Doyen1,2, Fabien Montel2,3, Thierry Gautier1, Hervé Menoni2,4, Cyril Claudet5, Marlène Delacour-Larose1, Dimitri Angelov2,4, Ali Hamiche6, Jan Bednar5,a, Cendrine Faivre-Moskalenko2,3, Philippe Bouvet2,4 and Stefan Dimitrov1,2

  1. Institut Albert Bonniot, INSERM U309, La Tronche cedex, France
  2. Laboratoire Joliot-Curie, Ecole Normale Supérieure de Lyon, Lyon, France
  3. Laboratoire de Physique, CNRS UMR 5672, Ecole Normale Supérieure de Lyon, Lyon, France
  4. Laboratoire de Biologie Moléculaire de la Cellule, CNRS-UMR 5161/INRA 1237/IFR128 Biosciences, Ecole Normale Supérieure de Lyon, Lyon, France
  5. CNRS, Laboratoire de Spectrometrie Physique, UMR 5588, St Martin d'Heres Cedex, France
  6. Institut André Lwoff, CNRS UPR 9079, Villejuif, France

Correspondence to:

Philippe Bouvet, Laboratoire de Biologie Moléculaire de la Cellule, CNRS-UMR 5161/INRA 1237/IFR128 Biosciences, Ecole Normale Supérieure de Lyon, 46 Allée d'Italie, 69007 Lyon, France. Tel./Fax: +33 4 72 72 8016; E-mail: pbouvet@ens-lyon.fr

Stefan Dimitrov, Laboratoire de Biologie Moléculaire de la Cellule, CNRS-UMR 5161/INRA 1237/IFR128 Biosciences, Ecole Normale Supérieure de Lyon, 46 Allée d'Italie, 69007 Lyon, France. Tel.: +33 4 76 54 94 73; Fax: +33 4 76 54 95 95; E-mail: stefan.dimitrov@ujf-grenoble.fr

aPresent address: Department of Cell Biology, Institute of Physiology, Academy of Sciences of the Czech Republic and Institute of Cellular Biology and Pathology, First Faculty of Medicine, Charles University in Prague, Albertov 4, 128 01 Prague 2, Czech Republic

Received 28 April 2006; Accepted 31 July 2006

The histone variant H2A.Bbd appeared to be associated with active chromatin, but how it functions is unknown. We have dissected the properties of nucleosome containing H2A.Bbd. Atomic force microscopy (AFM) and electron cryo-microscopy (cryo-EM) showed that the H2A.Bbd histone octamer organizes only approx130 bp of DNA, suggesting that 10 bp of each end of nucleosomal DNA are released from the octamer. In agreement with this, the entry/exit angle of the nucleosomal DNA ends formed an angle close to 180° and the physico-chemical analysis pointed to a lower stability of the variant particle. Reconstitution of nucleosomes with swapped-tail mutants demonstrated that the N-terminus of H2A.Bbd has no impact on the nucleosome properties. AFM, cryo-EM and chromatin remodeling experiments showed that the overall structure and stability of the particle, but not its property to interfere with the SWI/SNF induced remodeling, were determined to a considerable extent by the H2A.Bbd docking domain. These data show that the whole H2A.Bbd histone fold domain is responsible for the unusual properties of the H2A.Bbd nucleosome.

  • Keywords:

    • chromatin,
    • H2A.Bbd,
    • histone variant,
    • nucleosome remodeling,
    • nucleosome stability