Dissection of the unusual structural and functional properties of the variant H2A.Bbd nucleosome.
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 approximately 130 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 degrees 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.
Doyen
Cécile-Marie
CM
Institut Albert Bonniot, INSERM U309, La Tronche cedex, France.
Montel
Fabien
F
Gautier
Thierry
T
Menoni
Hervé
H
Claudet
Cyril
C
Delacour-Larose
Marlène
M
Angelov
Dimitri
D
Hamiche
Ali
A
Bednar
Jan
J
Faivre-Moskalenko
Cendrine
C
Bouvet
Philippe
P
Dimitrov
Stefan
S
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D042002:Chromatin Assembly and Disassembly; D002868:Chromosomal Proteins, Non-Histone / Q000737:chemistry / Q000378:metabolism; D020285:Cryoelectron Microscopy; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D014644:Genetic Variation; D006657:Histones / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D066298:In Vitro Techniques; D018625:Microscopy, Atomic Force; D008969:Molecular Sequence Data; D009154:Mutation; D009707:Nucleosomes / Q000378:metabolism*; D017510:Protein Folding; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D029867:Xenopus Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D014982:Xenopus laevis
D002868:Chromosomal Proteins, Non-Histone; D006657:Histones; D009707:Nucleosomes; D011994:Recombinant Proteins; D029867:Xenopus Proteins; D004247:DNA