Synthesis of ubiquitylated histone H3 using a thiirane linker for chemical ligation.

Post-translational modifications of histone proteins, which form nucleosome cores, play an important role in gene regulation. Ubiquitin modification is one such modification. We previously reported on the use of a thiirane linker to introduce a 1,2-aminothiol moiety at a cysteine residue for native chemical ligation with peptide thioesters, which permitted isopeptide mimetics to be produced. In this report, we describe the preparation of the ubiquitylated full length histone H3 at the 18 position and the construction of tetranucleosomes with recombinant histones H2A, H2B, H4, and DNA, which are slightly more stable than those that are prepared without ubiquitin modification.