Abstract

The three-dimensional organisation of the DNA is one of the great marvels of physical biology. By winding around a special class of proteins, the metre-long DNA manages to compress enormously to fit inside tiny (6 μm) nuclei, avoid entanglement and, moreover, maintain exquisite control over the accessibility of the information it carries. The structure of this remarkable complex of DNA and proteins, known as chromatin, determines how easy the DNA can be accessed and, thus, it is intimately linked to gene expression regulation. However, chromatin structure and its modulation are not fully understood. In this talk, I will explain how the structure of chromatin is much more fluid and tuneable than originally proposed, which explains how chromatin achieves various different roles in vivo according to the transcriptional state, cell-cycle stage, or in response to environmental signals (Collepardo and Schlick, PNAS 2014 ). I will also discuss how multiscale modelling can be used to reveal the molecular mechanisms behind epigenetic control of chromatin structure and provide a link between epigenomes, structure, and gene function (Collepardo et al., JACS , 2015).