A new study has examined a specific chemical modification called acetylation at lysine 115 on histone H3 (H3K115ac), which is located inside the core nucleosome at a critical position that affects its structure. Inside our cells, DNA is wound around a ball of proteins called histones, forming structures known as nucleosomes. Chemical tags added to histones help control how tightly DNA is packaged into nucleosomes and whether genes are turned on or off.These tags are often called epigenetic marks and most epigenetic research focuses on the tags found on the histone ‘tails’ that protrude from the nucleosome. New epigenetic marker The study, led by researchers at the Institute of Genetics and Cancer, mapped where the H3K115ac modification is located across the genome, revealing that it is at key sites that control gene expression.Notably, H3K115ac was enriched on unstable ‘fragile’ nucleosomes making the DNA more exposed and easier to access. This suggests that H3K115ac may actively contribute to loosening DNA structure in our cells and makes H3K115ac a powerful new epigenetic marker for identifying important regulatory regions that control gene activity in mammalian genomes. This study provides the first genome-wide characterisation of H3K115 acetylation and identifies a striking and previously unappreciated association of this globular-domain histone modification with fragile nucleosomes at CpG island promoters, active enhancers, and CTCF binding sites. Professor Wendy Bickmore Director of MRC Human Genetics Unit Related links Read the paper in eLife Wendy Bickmore Research Group Tags 2026 Publication date 10 Mar, 2026
