Nucleosome under NMR’s eye – A practical guide

Regulation of gene expression, DNA replication, and repair, all converge on chromatin and its repeating unit, the nucleosome. Nucleosomes are inherently dynamic macromolecular assemblies that are bound and manipulated by a wide array of proteins. Structural biology of nucleosomes is a large and exciting field that is in need of a range of complementary techniques. With the introduction of advanced, high-resolution solution and, since recently, solid-state NMR techniques to the nucleosome, NMR offers an attractive alternative to crystallographic and microscopic methods to uncover the molecular mechanisms in chromatin biology. In this article, we review the practical aspects of nucleosome studies by NMR. After a brief description of nucleosome structure and functions, and outlining some of the main questions in the field, we highlight the key aspects in the preparation of nucleosome samples. We then review the application of backbone-based and methyl-TROSY solution-state NMR and¹³ C-and¹ H-detected solid-state NMR. Finally, we detail the advantages and limitations of these approaches.