Chromatin structure revealed by X-ray scattering analysis and computational modeling.
It remains unclear how the 2m of human genomic DNA is organized in each cell. The textbook model has long assumed that the 11-nm-diameter nucleosome fiber (beads-on-a-string), in which DNA is wrapped around core histones, is folded into a 30-nm chromatin fiber. One of the classical models assumes that the 30-nm chromatin fiber is further folded helically to form a larger fiber. Small-angle X-ray scattering (SAXS) is a powerful method for investigating the bulk structure of interphase chromatin and mitotic chromosomes. SAXS can detect periodic structures in biological materials in solution. In our SAXS results, no structural feature larger than 11 nm was detected. Combining this with a computational analysis of "in silico condensed chromatin" made it possible to understand more about the X-ray scattering profiles and suggested that the chromatin in interphase nuclei and mitotic chromosomes essentially consists of irregularly folded nucleosome fibers lacking the 30-nm chromatin structure. In this article, we describe the experimental details of our SAXS and modeling systems. We also discuss other methods for investigating the chromatin structure in cells.
['Maeshima|Kazuhiro|K|', 'Imai|Ryosuke|R|', 'Hikima|Takaaki|T|', 'Joti|Yasumasa|Y|']
D002843:Chromatin D003198:Computer Simulation D006367:HeLa Cells D006801:Humans D008958:Models, Molecular D008968:Molecular Conformation D053838:Scattering, Small Angle D014961:X-Ray Diffraction
Chromatin Computational modeling 30-nm chromatin fiber Small-angle X-ray scattering Chromosomes Cryo-electron microscopy