Chemical modifications of histones, such as lysine acetylation and ubiquitination, play pivotal roles in epigenetic regulation of gene expression. Methods to alter the epigenome thus hold promise as tools for elucidating epigenetic mechanisms and as therapeutics. However, an entirely chemical method to introduce histone modifications in living cells without genetic manipulation is unprecedented. Here, we developed a chemical catalyst, PEG-LANA-DSSMe 11, that binds with nucleosome’s acidic patch and promotes regioselective, synthetic histone acetylation at H2BK120 in living cells. The size of polyethylene glycol in the catalyst was a critical determinant for its in-cell metabolic stability, binding affinity to histones, and high activity. The synthetic acetylation promoted by 11 without genetic manipulation competed with and suppressed physiological H2B ubiquitination, a mark regulating chromatin functions, such as transcription and DNA damage response. Thus, the chemical catalyst will be a useful tool to manipulate epigenome for unraveling epigenetic mechanisms in living cells.
<div><div><div><p>Chemical modifications of histones play a pivotal role in the epigenome and regulation of gene expression, and their abnormality is tightly linked to numerous disease states in humans. Therefore, chemical tools to manipulate epigenome hold promise for both therapy and the elucidation of epigenetic mechanisms. We previously developed the chemical catalyst LANA-DSH, which binds to nucleosomes via a LANA peptide ligand, and selectively acylates proximal histone H2BK120 to the catalyst moiety by acti- vating acyl-CoAs. Thus far, however, histone acylation by a chem- ical catalyst system in living cells has not yet been demonstrated. Here, we report a chemical catalyst system, composed of a nucleo- some-binding catalyst (PEG-LANA-DSH) and a cell-permeable thioester acyl donor (NAC-acyl), that can promote regioselective lysine acylation of histones in living cells. Whereas LANA-DSH is rapidly decomposed in cells, attachment of polyethylene glycol (PEG) to the LANA moiety can prevent this undesired degradation. Increasing the size of PEG conferred LANA with greater in-cell stability, but reduced catalytic activity, indicating that there is an optimum PEG length balancing stability and catalytic activity. The optimized PEG-LANA-DSH catalyst 11 efficiently promoted H2BK120 acetylation in living cells, which subsequently sup- pressed ubiquitination of H2BK120, a mark regulating various chromatin functions, such as transcription and DNA damage re- sponse. Thus, our chemical catalyst system will be useful as a unique tool to manipulate the epigenome for therapeutic purposes or further understanding epigenetic mechanisms.</p></div></div></div>
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