title: Histone H1 and chromatin interactions in human fibroblast nuclei after H1 depletion and reconstitution with H1 subfractions.
abstract: BACKGROUND
  Linker histones constitute a family of lysine-rich proteins associated with nucleosome core particles and linker DNA in eukaryotic chromatin. In permeabilized cells, they can be extracted from nuclei by using salt concentration in the range of 0.3 to 0.7 M. Although other nuclear proteins are also extracted at 0.7 M salt, the remaining nucleus represents a template that is relatively intact.
  
  
  METHODS
  A cytochemical method was used to study the affinity of reconstituted linker histones for chromatin in situ in cultured human fibroblasts. We also investigated their ability to condense chromatin by using DNA-specific osmium ammine staining for electron microscopy.
  
  
  RESULTS
  Permeabilized and H1-depleted fibroblast nuclei were suitable for the study of linker histone-chromatin interactions after reconstitution with purified linker histone subfractions. Our results showed that exogenous linker histones bind to chromatin with lower affinity than the native ones. We detected no significant differences between the main H1 and H1 degrees histone fractions with respect to their affinity for chromatin or in their ability to condense chromatin.
  
  
  CONCLUSIONS
  Linker histone interactions with chromatin are controlled also by mechanisms independent of linker histone subtype composition.
authors.affiliation: Institute of Molecular Biology, Bulgarian Academy of Sciences, Sofia, Bulgaria.
authors.forename: Nora N
authors.initials: NN
authors.lastname: Kostova
authors.forename: Ljuba
authors.initials: L
authors.lastname: Srebreva
authors.forename: Dimiter V
authors.initials: DV
authors.lastname: Markov
authors.forename: Ingemar
authors.initials: I
authors.lastname: Rundquist
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism*; D002843:Chromatin / Q000737:chemistry / Q000378:metabolism*; D005347:Fibroblasts / Q000166:cytology*; D006657:Histones / Q000172:deficiency* / Q000302:isolation & purification / Q000378:metabolism*; D006801:Humans; D051379:Mice; D011485:Protein Binding
chemical_list: D002843:Chromatin; D006657:Histones; C024063:nuclear protein H1(0)