Nucleosome sliding induced by the xMi-2 complex does not occur exclusively via a simple twist-diffusion mechanism.
ATP-dependent chromatin remodeling complexes can induce the translocation (sliding) of nucleosomes in cis along DNA, but the mechanism by which sliding occurs is not well defined. We previously presented evidence that sliding induced by the human SWI/SNF complex does not occur solely via a proposed "twist-diffusion" mechanism whereby the DNA rotates about its helical axis without displacement from the surface of the nucleosome (Aoyagi, S., and Hayes, J. J. (2002) Mol. Cell. Biol. 22, 7484-7490). Here we examined whether the Xenopus Mi-2 nucleosome remodeling complex induces nucleosome sliding via a twist-diffusion mechanism with nucleosomes assembled onto DNA templates containing branched DNA structures expected to sterically hinder rotation of the DNA helix on the nucleosome surface. We find that the branched DNA-containing nucleosomes undergo xMi-2-catalyzed sliding at a rate and extent identical to that of nucleosomes assembled on native DNA fragments. These results indicate that both the hSWI/SNF and xMi-2 complexes induce nucleosome sliding via a mechanism(s) other than simple twist diffusion and are consistent with models in which the DNA largely maintains its rotational orientation with respect to the histone surface.
Aoyagi
Sayura
S
Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, New York 14642, USA.
Wade
Paul A
PA
Hayes
Jeffrey J
JJ
D000818:Animals; D001483:Base Sequence; D002843:Chromatin / Q000737:chemistry*; D004247:DNA / Q000737:chemistry; D015252:Deoxyribonucleases, Type II Site-Specific; D005090:Exodeoxyribonucleases; D006657:Histones / Q000737:chemistry; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009707:Nucleosomes / Q000737:chemistry* / Q000235:genetics; D015183:Restriction Mapping; D014981:Xenopus
D002843:Chromatin; D006657:Histones; D009707:Nucleosomes; D004247:DNA; D005090:Exodeoxyribonucleases; C020133:exodeoxyribonuclease III; C035042:endodeoxyribonuclease FokI; D015252:Deoxyribonucleases, Type II Site-Specific