A Nonenzymatic Modification of the Amino-terminal Domain of Histone H3 by Bile Acid Acyl Adenylate

Abstract

Although it has been proposed that the secondary bile acids, deoxycholic acid and lithocholic acid, increase the number of aberrant crypt foci in the colon and may act as colon tumor promoters, there is little evidence detailing their mechanism of action. Histones play an important role in controlling gene expression, and the posttranslational modification of histones plays a role in regulation of intracellular signal transduction. In particular, the amino-terminal tail domain of histone H3 is sensitive to several posttranslational modifications, and acetylation of this domain changes its electrostatic environment and results in the loss of native folding. Therefore, we studied the modification of ⑀-amino groups on human histone H3 by deoxycholyl adenylate, which is an active intermediate in deoxycholyl thioester biosynthesis. After incubation of recombinant human histone H3 with a smaller amount of acyl adenylate, followed by enzymatic digestion, the peptide fragment mixtures were analyzed by matrix-assisted laser desorption ionization mass spectrometry. These data showed the formation of only one adduct fragment, which corresponded to amino acids 3-8 with a deoxycholate adduct, suggesting that the ⑀-amino group of Lys 4 had the highest reactivity. This novel modification, formation of a bile acid adduct on the histone H3 amino-terminal tail domain through an active acyl adenylate, may relate to the carcinogenesis-promoting effects of secondary bile acids.

Initial characterization of histone H3 serine 10 O-acetylation

“…However, we cannot rule out that this mark might be added to histones in a non-enzymatic process, as has been shown through investigations of different marks on proteins including histones. [28][29][30] Interestingly, in yeast we found a co-occurrence of H3S28ac and nearby H3S31ac. This S31 residue is found only on the H3 variant H3.3 in mammalian cells (which is the only sequence found in yeast), and could provide an H3 variant specific PTM, which is quite rare.…”

Analysis of bile acid glutathione thioesters by liquid chromatography/electrospray ionization–tandem mass spectrometry

“…The acyl-adenylate has an electrophilic carbonyl-carbon and spontaneously reacts with the amino group of taurine [3], substance P [5], lysozyme [5], and histone [6] in a phosphate buffer solution, indicating a higher reactivity of the acyl-adenylate toward amino group. BAs are metabolized to their acyl-glucuronides [7][8][9][10][11] and react in vitro with proteins, resulting in BA-protein adducts [12].…”

Immunoprecipitation and MALDI-MS identification of lithocholic acid-tagged proteins in liver of bile duct-ligated rats

“…Finally adenylation with AMP has also been observed under in vitro conditions (24). In principle, the CoA thioester, the acyl glucuronide, or the adenylate should be capable of binding irreversibly to proteins (18,25,26). However, no detailed study on the structural analysis of protein-bound LCA formed in the liver has been reported.…”

“…LCA acyl-adenylate (LCA-AMP) was chemically synthesized by the method previously reported (26). The synthetic products were purified by column chromatography on Sephadex LH-20 (40 3 1.5 cm ID) using 40% methanol as the eluent at a flow rate of 18 ml/h.…”