Remosomes: RSC generated non-mobilized particles with approximately 180 bp DNA loosely associated with the histone octamer.
Chromatin remodelers are sophisticated nano-machines that are able to alter histone-DNA interactions and to mobilize nucleosomes. Neither the mechanism of their action nor the conformation of the remodeled nucleosomes are, however, yet well understood. We have studied the mechanism of Remodels Structure of Chromatin (RSC)-nucleosome mobilization by using high-resolution microscopy and biochemical techniques. Atomic force microscopy and electron cryomicroscopy (EC-M) analyses show that two types of products are generated during the RSC remodeling: (i) stable non-mobilized particles, termed remosomes that contain about 180 bp of DNA associated with the histone octamer and, (ii) mobilized particles located at the end of DNA. EC-M reveals that individual remosomes exhibit a distinct, variable, highly-irregular DNA trajectory. The use of the unique "one pot assays" for studying the accessibility of nucleosomal DNA towards restriction enzymes, DNase I footprinting and ExoIII mapping demonstrate that the histone-DNA interactions within the remosomes are strongly perturbed, particularly in the vicinity of the nucleosome dyad. The data suggest a two-step mechanism of RSC-nucleosome remodeling consisting of an initial formation of a remosome followed by mobilization. In agreement with this model, we show experimentally that the remosomes are intermediate products generated during the first step of the remodeling reaction that are further efficiently mobilized by RSC.
Shukla
Manu Shubhdarshan
MS
Université Joseph Fourier-Grenoble 1, Institut National de la Santé et de la Recherche Médicale, Institut Albert Bonniot, U823, Site Santé-BP 170, 38042 Grenoble Cedex 9, France.
Syed
Sajad Hussain
SH
Montel
Fabien
F
Faivre-Moskalenko
Cendrine
C
Bednar
Jan
J
Travers
Andrew
A
Angelov
Dimitar
D
Dimitrov
Stefan
S
D000818:Animals; D042002:Chromatin Assembly and Disassembly; D020285:Cryoelectron Microscopy; D004247:DNA / Q000737:chemistry* / Q000648:ultrastructure; D006657:Histones / Q000737:chemistry* / Q000648:ultrastructure; D066298:In Vitro Techniques; D018625:Microscopy, Atomic Force; D009690:Nucleic Acid Conformation; D009707:Nucleosomes / Q000737:chemistry* / Q000648:ultrastructure; D020836:Protein Structure, Quaternary; D014982:Xenopus laevis
D006657:Histones; D009707:Nucleosomes; D004247:DNA