The DNA chaperone HMGB1 facilitates ACF/CHRAC-dependent nucleosome sliding.
Nucleosome remodelling complexes CHRAC and ACF contribute to chromatin dynamics by converting chemical energy into sliding of histone octamers on DNA. Their shared ATPase subunit ISWI binds DNA at the sites of entry into the nucleosome. A prevalent model assumes that DNA distortions catalysed by ISWI are converted into relocation of DNA relative to a histone octamer. HMGB1, one of the most abundant nuclear non-histone proteins, binds with preference to distorted DNA. We have now found that transient interaction of HMGB1 with nucleosomal linker DNA overlapping ISWI-binding sites enhances the ability of ACF to bind nucleosomal DNA and accelerates the sliding activity of limiting concentrations of remodelling factor. By contrast, an HMGB1 mutant with increased binding affinity was inhibitory. These observations are consistent with a role for HMGB1 as a DNA chaperone facilitating the rate-limiting DNA distortion during nucleosome remodelling.
Bonaldi
Tiziana
T
Adolf-Butenandt Institut, Molekularbiologie, Schillerstrasse 44, D-80336 München, Germany.
Längst
Gernot
G
Strohner
Ralf
R
Becker
Peter B
PB
Bianchi
Marco E
ME
D000818:Animals; D001665:Binding Sites; D002843:Chromatin / Q000378:metabolism*; D004247:DNA / Q000378:metabolism*; D018983:DNA Footprinting; D004305:Dose-Response Relationship, Drug; D004330:Drosophila; D024243:HMGB1 Protein / Q000378:metabolism*; D051379:Mice; D008954:Models, Biological; D009154:Mutation; D009707:Nucleosomes / Q000378:metabolism*; D011485:Protein Binding; D011994:Recombinant Proteins / Q000378:metabolism*; D013997:Time Factors
D002843:Chromatin; D024243:HMGB1 Protein; D009707:Nucleosomes; D011994:Recombinant Proteins; D004247:DNA