Computer models explain how histones establish contacts in the cell nucleus and regulate accessibility

Abstract

The spatial structure of chromatin is diverse and crucial for gene activity. Computer models help to understand the effects of various factors on the structure. The arrangement of nucleosomes along the DNA plays an important role. The length of the connecting DNA (linker DNA) regulates the global structure: a uniform distribution of nucleosomes along the DNA favours more regular structures as seen in interphase, while an irregular distribution tends to result in a more random spatial arrangement as in metaphase chromatin. Even a small shift of a single nucleosome can affect the contacts between distant DNA regions. In active gene regions, the number of bound nucleosomes is variable, while in inactive regions the number of linker histones varies. Loop structures in the genome change with the distribution of nucleosomes.