Histone chaperone‐mediated co‐expression assembly of tetrasomes and nucleosomes

Abstract

The nucleosome, a basic unit of chromatin found in all eukaryotes, is thought to be assembled through the orchestrated activity of several histone chaperones and chromatin assembly factors in a stepwise manner, proceeding from tetrasome assembly, to H2A/H2B deposition, and finally to formation of the mature nucleosome. In this study, we demonstrate chaperone‐mediated assembly of both tetrasomes and nucleosomes on the well‐defined Widom 601 positioning sequence using a co‐expression/reconstitution wheat germ cell‐free system. The purified tetrasomes and nucleosomes were positioned around the center of a given sequence. The heights and diameters were measured by atomic force microscopy. Together with the reported unmodified native histones produced by the wheat germ cell‐free platform, our method is expected to be useful for downstream applications in the field of chromatin research.

Keywords

• nucleosome
• tetrasome
• NAP1
• wheat germ cell‐free synthesis
• AFM