Synthesis of Oriented Hexasomes and Asymmetric Nucleosomes Using a Template Editing Process

Area of Science:

• Molecular Biology
• Epigenetics
• Structural Biology

Background:

• Nucleosomes, the fundamental units of chromatin, exhibit pseudo-symmetry.
• Breaking this symmetry generates asymmetric nucleosomes and hexasomes, implicated in gene regulation.
• Current methods for preparing these noncanonical substrates are inefficient, limiting their use.

Purpose of the Study:

• To develop an efficient strategy for preparing oriented asymmetric nucleosomes and hexasomes.
• To enable precise control over the orientation of these structures relative to DNA sequences.
• To investigate the functional impact of nucleosome asymmetry on chromatin remodeling.

Main Methods:

• Utilizing truncated DNA templates for assembling oriented hexasomes.
• Employing DNA ligation and addition of heterotypic histones to form asymmetric nucleosomes.
• Generating desymmetrized mononucleosomes and oligonucleosomes with controlled DNA overhangs and histone compositions.

Main Results:

• Demonstrated a novel strategy for controlled assembly of asymmetric nucleosomes and hexasomes.
• Showcased compatibility with various nucleosome positioning sequences.
• Revealed that cancer-associated histone mutations can alter BAF complex chromatin remodeling activity, leading to aberrant chromatin structures.

Conclusions:

• The developed technology provides efficient access to oriented asymmetric nucleosomes and hexasomes.
• This advancement facilitates functional studies of chromatin remodeling.
• Cancer-associated histone mutations can reprogram chromatin remodeling complexes, contributing to aberrant chromatin structures in cancer.