Chromatin is the substrate for most processes that occur in the
eukaryotic cell nucleus due to its role as the universal genome
packaging state. The nucleosome is the fundamental repeating
subunit of chromatin so it is unsurprising that the histone
proteins organising this structure are highly conserved. The
design principles of the nucleosome are not understood despite
its importance and conservation. Our aim is to understand the
structure-function relationships of chromatin in molecular
detail. Most textbooks represent nucleosomes as static ‘tuna
cans’ that provide a solution to the ‘packaging problem’ of
compacting metres of genomic DNA into the micrometre diameter
cell nucleus. In fact, this could be achieved by any small and
highly positively charged ionic compound. Determinants of
nucleosome dynamics Nucleosomes appear to have evolved to
provide a unique balance of static organisation and dynamic
character that can undergo specific transitions such as sliding
or histone exchange which are essential for