title: HMGN proteins act in opposition to ATP-dependent chromatin remodeling factors to restrict nucleosome mobility.
abstract: The high-mobility group N (HMGN) proteins are abundant nonhistone chromosomal proteins that bind specifically to nucleosomes at two high-affinity sites. Here we report that purified recombinant human HMGN1 (HMG14) and HMGN2 (HMG17) potently repress ATP-dependent chromatin remodeling by four different molecular motor proteins. In contrast, mutant HMGN proteins with double Ser-to-Glu mutations in their nucleosome-binding domains are unable to inhibit chromatin remodeling. The HMGN-mediated repression of chromatin remodeling is reversible and dynamic. With the ACF chromatin remodeling factor, HMGN2 does not directly inhibit the ATPase activity but rather appears to reduce the affinity of the factor to chromatin. These findings suggest that HMGN proteins serve as a counterbalance to the action of the many ATP-dependent chromatin remodeling activities in the nucleus.
authors.affiliation: Section of Molecular Biology, University of California, San Diego, La Jolla, CA 92093-0347, USA.
authors.forename: Barbara P
authors.initials: BP
authors.lastname: Rattner
authors.forename: Timur
authors.initials: T
authors.lastname: Yusufzai
authors.forename: James T
authors.initials: JT
authors.lastname: Kadonaga
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D002843:Chromatin / Q000378:metabolism; D042002:Chromatin Assembly and Disassembly / Q000502:physiology*; D004265:DNA Helicases / Q000378:metabolism; D024241:HMGN1 Protein / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D024242:HMGN2 Protein / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D020409:Molecular Motor Proteins / Q000502:physiology; D009154:Mutation; D009687:Nuclear Proteins / Q000378:metabolism; D009707:Nucleosomes / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism
chemical_list: C411647:A1CF protein, human; D002843:Chromatin; D024241:HMGN1 Protein; D024242:HMGN2 Protein; D020409:Molecular Motor Proteins; D009687:Nuclear Proteins; D009707:Nucleosomes; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; D014157:Transcription Factors; D000255:Adenosine Triphosphate; C084108:SMARCA4 protein, human; D004265:DNA Helicases