An experimental design to extract more information from MS-based histone studies

Area of Science:

• Biochemistry
• Proteomics
• Epigenetics

Background:

• Histone posttranslational modifications (hPTMs) are crucial for eukaryotic genome complexity and are often described by the

Purpose of the Study:

• To address the challenge of unannotated MSMS spectra in histone proteomics due to combinatorial complexity.
• To develop a "quantify-first" strategy for isolating and analyzing previously unannotated histone ion populations.
• To improve the identification and assessment of histone modifications, particularly acetylation.

Main Methods:

• Implemented a time-lapse enzymatic deacetylation using HDAC1 on commercial histone extract.
• Adapted mass spectrometry (MSMS) search parameters to investigate sample preparation, data acquisition, and analysis issues.
• Utilized a "quantify-first" approach to isolate ion populations of interest.

Main Results:

• Successfully doubled the annotated portion of precursors from 10.5% to 21.6%.
• Demonstrated a strategy to mitigate the lack of validated false discovery rate (FDR) control for combinatorial PTMs.
• Identified several workflow adaptations to reduce the "dark histone ion space" in future analyses.

Conclusions:

• The proposed enzymatic deacetylation strategy is effective for analyzing histone modifications, especially acetylation.
• This method enhances the identification of relevant histone ions and aids in understanding the histone code.
• The strategy is adaptable for various enzymes targeting specific modifications, offering broad applicability in proteomics.