An MNase-ChIP-Seq Protocol to Profile Histone Modifications at a DNA Break in Yeast.

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• Eukaryotic DNA is organized by wrapping around histone proteins to form nucleosomes.
• Histone post-translational modifications (PTMs) are crucial for regulating chromatin structure, gene expression, and DNA repair pathways.
• Understanding how PTMs change in response to DNA damage, such as DNA double-strand breaks (DSBs), is vital for cellular function.

Purpose of the Study:

• To establish a robust chromatin immunoprecipitation protocol combined with micrococcal nuclease digestion and DNA sequencing (MNase-ChIP-seq).
• To map the genome-wide distribution of histone modifications following the induction of a single DSB in *Saccharomyces cerevisiae*.
• To provide a reliable method for analyzing histone PTMs in yeast under various conditions.

Main Methods:

• Chromatin immunoprecipitation (ChIP) coupled with micrococcal nuclease (MNase) digestion and DNA sequencing (ChIP-seq).
• Induction of a single DSB using the HO endonuclease in *Saccharomyces cerevisiae*.
• Detection and analysis of histone H3 methylation changes.

Main Results:

• Successfully mapped the genome-wide distribution of histone modifications after DSB induction.
• Validated the MNase-ChIP-seq method by observing changes in histone H3 methylation upon HO transcriptional activation and DSB induction.
• Demonstrated the protocol's ability to detect alterations in histone PTMs.

Conclusions:

• The developed MNase-ChIP-seq protocol is a robust tool for studying histone PTMs in yeast.
• This method facilitates the analysis of chromatin dynamics and PTMs in response to DNA damage.
• The protocol supports research on gene expression and DNA repair mechanisms in yeast mutant strains or under stress conditions.