Metastable macromolecular complexes containing high mobility group nucleosome-binding chromosomal proteins in HeLa nuclei.
High mobility group nucleosome-binding (HMGN) proteins belong to a family of nuclear proteins that bind to nucleosomes and enhance transcription from chromatin templates by altering the structure of the chromatin fiber. The intranuclear organization of these proteins is dynamic and related to the metabolic state of the cell. Here we report that approximately 50% of the HMGN proteins are organized into macromolecular complexes in a fashion that is similar to that of other nuclear activities that modify the structure of the chromatin fiber. We identify several distinct HMGN-containing complexes that are relatively unstable and find that the inclusion of HMGN in the complexes varies according to the metabolic state of the cell. The nucleosome binding ability of HMGN in the complex is stronger than that of the free HMGN. We suggest that the inclusion of HMGN proteins into metastable multiprotein complexes serves to target the HMGN proteins to specific sites in chromatin and enhances their interaction with nucleosomes.
Lim
Jae-Hwan
JH
Protein Section, CCR, NCI, National Institutes of Health, Bethesda, Maryland 20892, USA.
Bustin
Michael
M
Ogryzko
Vasily V
VV
Postnikov
Yuri V
YV
D000546:Amanitins / Q000494:pharmacology; D002467:Cell Nucleus / Q000378:metabolism*; D002846:Chromatography, Affinity; D004591:Electrophoresis, Polyacrylamide Gel; D006367:HeLa Cells; D006609:High Mobility Group Proteins / Q000378:metabolism*; D006801:Humans; D018613:Microscopy, Confocal; D009707:Nucleosomes / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D000546:Amanitins; D006609:High Mobility Group Proteins; D009707:Nucleosomes