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Abstract Histone post-translational modifications (PTMs) participate in the dynamic regulation of chromatin structure and function, through their chemical nature and specific location within the histone sequence. Alternative analytical approaches for histone PTM studies are required to facilitate the differentiation between ubiquitously present isomers and the detection of low-abundance PTMs Here, we report a high-sensitivity bottom-up method based on nano-liquid chromatography (nLC), trapped ion mobility spectrometry (TIMS), data-dependent acquisition (DDA), parallel accumulation-serial fragmentation (PASEF), and high-resolution time-of-flight tandem mass spectrometry (ToF-MS/MS) for the analysis of histone PTMs. This method was tested in a threatened coral species, the staghorn coral Acropora cervicornis, during an episode of acute thermal stress. The obtained results allowed for the identification of PTM changes in core histones involved in the coral’s heat response. Compared to traditional LC-MS/MS approaches, the incorporation of TIMS and ddaPASEF MS/MS resulted in a highly specific and sensitive method with a wide dynamic range (6 orders of magnitude). This depth of analysis allows for the simultaneous measurement of low-abundance PTM signatures relative to the unmodified form. An added advantage is the ability to mass- and mobility-isolate prior to peptide sequencing, resulting in higher confidence identification of epigenetic markers associated with heat stress in corals (e.g. increased H4 4–17 with 2ac and 3ac, and decreases in H4 4–17 K12ac, K16ac, H4 K20me2, and H2A K5ac, K7ac, K9ac, K12ac, K14ac, and K74ac).
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Histone Acid Extraction and High Throughput Mass Spectrometry to Profile Histone Modifications in Arabidopsis thaliana
Abstract Histone post‐translational modifications (PTMs) play important roles in many biological processes, including gene regulation and chromatin dynamics, and are thus of high interest across many fields of biological research. Chromatin immunoprecipitation coupled with sequencing (ChIP‐seq) is a powerful tool to profile histone PTMsin vivo. This method, however, is largely dependent on the specificity and availability of suitable commercial antibodies. While mass spectrometry (MS)–based proteomic approaches to quantitatively measure histone PTMs have been developed in mammals and several other model organisms, such methods are currently not readily available in plants. One major challenge for the implementation of such methods in plants has been the difficulty in isolating sufficient amounts of pure, high‐quality histones, a step rendered difficult by the presence of the cell wall. Here, we developed a high‐yielding histone extraction and purification method optimized forArabidopsis thalianathat can be used to obtain high‐quality histones for MS. In contrast to other methods used in plants, this approach is relatively simple, and does not require membranes or additional specialized steps, such as gel excision or chromatography, to extract highly purified histones. We also describe methods for producing MS‐ready histone peptides through chemical labeling and digestion. Finally, we describe an optimized method to quantify and analyze the resulting histone PTM data using a modified version of EpiProfile 2.0 for Arabidopsis. In all, the workflow described here can be used to measure changes to histone PTMs resulting from various treatments, stresses, and time courses, as well as in different mutant lines. © 2022 Wiley Periodicals LLC. Basic Protocol 1: Nuclear isolation and histone acid extraction Basic Protocol 2: Peptide labeling, digestion, and desalting Basic Protocol 3: Histone HPLC‐MS/MS and data analysis
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- Award ID(s):
- 2228767
- PAR ID:
- 10370974
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Current Protocols
- Volume:
- 2
- Issue:
- 8
- ISSN:
- 2691-1299
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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