Imaging of Chromatin Fibers at Low Ionic-Strength & Mathematical Modeling

• Chromatin fibers exhibit irregular, three-dimensional morphology at low-ionic strength.
• Chicken erythrocyte chromatin fibers stripped of linker histones H1 and H5 exhibit a "beads-on-a-string" morphology.
• Modeling of the irregular, three-dimensional arrangement of nucleosomes in the chromatin fiber.
• Modeling of the effect of the removal of linker histone from chromatin fibers.
• Quantitative Measurements by AFM

Chromatin Fiber Compaction With Salt

• NaCl-induced compaction of the extended chromatin fiber, as visualized by AFM imaging.
• MgCl2-induced compaction of the extended chromatin fiber, as visualized by AFM imaging.

• Mild trypsin hydrolysis to analyze the contributions of the linker histone domains and the N-termini of core histone H3 to chromatin fiber structure.
• Reconstitution to selectively determine the contributions of the linker histone domains and the N-termini of core histone H3 to chromatin fiber structure.
  • Reconstitution of linker histone domains onto intact core histone octamer chromatin.
  • Reconstitution of linker histone domains onto H3-tailless chromatin.
  • Schematic presentation of reconstitution results.
  • How our results mesh with the crystal structure of the nucleosome