Real-Time Multistep Asymmetrical Disassembly of Nucleosomes and Chromatosomes Visualized by High-Speed Atomic Force...

Area of Science:

• Molecular Biology
• Genomics
• Biophysics

Background:

• Cellular machinery requires access to DNA within nucleosomes for genome processes.
• Nucleosomes are dynamic structures that can disassemble spontaneously or via molecular motors.
• Understanding nucleosome disassembly is crucial for controlling DNA accessibility.

Purpose of the Study:

• To visualize nucleosome and chromatosome disassembly in real-time.
• To analyze the role of linker histone H1 in nucleosome stability and disassembly.
• To investigate the dynamics of subnucleosomal intermediates like tetrasomes.

Main Methods:

• High-speed atomic force microscopy (HS-AFM) for imaging nucleosome dynamics.
• Development of a neural network and algorithm for real-time tracking of molecular structural changes.
• Deposition of nucleosomes and chromatosomes on mica for observation.

Main Results:

• Nucleosome disassembly is a sequential process involving asymmetrical dimer ejection.
• Linker histone H1 increases nucleosome stability and alters disassembly pathways.
• Tetrasomes are stable and exhibit mobility, potentially influencing nucleosome assembly and transcription.

Conclusions:

• Nucleosome disassembly is a regulated, stepwise process.
• Histone H1 significantly impacts nucleosome dynamics and stability.
• Tetrasome mobility is a key factor in nucleosome assembly and resilience during transcription.