Modulation of the nucleosome structure by histone acetylation

Area of Science:

• Molecular Biology
• Chromatin Biology
• Cell Biology

Background:

• Core particles are fundamental units of chromatin structure.
• Understanding modifications to core particles is crucial for studying gene regulation.
• Histone acetylation is a key epigenetic modification influencing chromatin accessibility.

Purpose of the Study:

• To develop a rapid isolation procedure for core particles from Chinese hamster ovary cells.
• To compare core particles from interphase, butyrate-treated, and metaphase cells.
• To investigate the impact of histone acetylation on histone-DNA and interhistone interactions.

Main Methods:

• Rapid isolation of core particles from Chinese hamster ovary cells.
• Analysis of core particles from various cellular states (interphase, butyrate-treated, metaphase).
• Comparison with chicken erythrocyte core particles.
• Assessment of histone acetylation, interhistone contacts, histone-DNA interactions, and thermal denaturation profiles.

Main Results:

• A rapid isolation method for core particles was established, allowing same-day measurements.
• Butyrate treatment increased acetylation of histones H3 and H4.
• Acetylation led to altered interhistone contacts and histone-DNA interactions.
• Changes included extended alpha-helical segments, altered H3 cysteine accessibility, and modified protamine displacement.
• Histone-DNA contacts were loosened, evident in thermal denaturation profiles.

Conclusions:

• Rapid isolation of core particles is feasible for immediate analysis.
• Histone acetylation, induced by butyrate, significantly alters chromatin structure.
• These structural changes impact histone-DNA interactions and accessibility, providing insights into epigenetic regulation.