title: Chromatin without the 30-nm fiber: constrained disorder instead of hierarchical folding.
abstract: Several hierarchical levels of DNA packaging are believed to exist in chromatin, starting from a 10-nm chromatin fiber that is further packed into a 30-nm fiber. Transitions between the 30-nm and 10-nm fibers are thought to be essential for the control of chromatin transcriptional status. However, recent studies demonstrate that in the nuclei, DNA is packed in tightly associated 10-nm fibers that are not compacted into 30-nm fibers. Additionally, the accessibility of DNA in chromatin depends on the local mobility of nucleosomes rather than on decompaction of chromosome regions. These findings argue for reconsidering the hierarchical model of chromatin packaging and some of the basic definitions of chromatin. In particular, chromatin domains should be considered as three-dimensional objects, which may include genomic regions that do not necessarily constitute a continuous domain on the DNA chain.
authors.affiliation: Institute of Gene Biology of the Russian Academy of Sciences; Moscow, Russia; Faculty of Biology; M.V. Lomonosov Moscow State University; Moscow, Russia; LIA 1066 French-Russian Joint Cancer Research Laboratory; Moscow, Russia.
authors.forename: Sergey V
authors.initials: SV
authors.lastname: Razin
authors.affiliation: Institute of Gene Biology of the Russian Academy of Sciences; Moscow, Russia; LIA 1066 French-Russian Joint Cancer Research Laboratory; Moscow, Russia.
authors.forename: Alexey A
authors.initials: AA
authors.lastname: Gavrilov
mesh_terms: D002843:Chromatin / Q000737:chemistry* / Q000378:metabolism; D042002:Chromatin Assembly and Disassembly; D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D042421:Histone Code; D006801:Humans; D014158:Transcription, Genetic
chemical_list: D002843:Chromatin; D004247:DNA
keywords: 3D genome organization; DNA packaging; chromatin domain; chromatin fiber; histone modifications; nucleosome mobility