The elastic resilience of DNA can induce all-or-none structural transitions in the nucleosome core particle.
DNA on the surface of the histone octamer in the native nucleosome core particle is modeled as a circumferentially wound elastic line on the surface of a cylinder. In a model for the radial transition, the line is allowed to straighten, and thus lose energy, by swinging off the surface, but it is impeded in such an excursion by a radial force field representing the attractive interaction between DNA and histone octamer. In a model for the axial transition, the line may straighten by becoming more parallel to a generator of the cylinder while remaining on the surface. In this mode of straightening, dimer-tetramer or tetramer-tetramer interfaces are disrupted, and the resulting energy gain impedes the transition. Both radial and axial transitions are predicted to occur in all-or-none fashion. We propose that these models are related to the abrupt transitions actually observed in the nucleosome core particle.
Marky
N L
NL
Department of Chemistry, Rutgers, State University of New Jersey, New Brunswick 08903.
Manning
G S
GS
D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D006657:Histones / Q000737:chemistry* / Q000378:metabolism; D008433:Mathematics; D008962:Models, Theoretical; D009707:Nucleosomes / Q000502:physiology / Q000648:ultrastructure*
D006657:Histones; D009707:Nucleosomes; D004247:DNA