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

Half a Century of Progress: The Evolution of Wheat Germ-Based In Vitro Translation into a Versatile Protein Production Method

The first demonstration of wheat germ extract (WGE)-based in vitro translation synthesising a protein from exogenously introduced messenger ribonucleic acid (mRNA) was published approximately fifty years ago. Since then, there have been numerous crucial improvements to the WGE-based in vitro translation, resulting in a significant increase in yield and the development of high-throughput protein-producing platforms. These developments have transformed the original setup into a versatile eukaryotic protein production method with broad applications. The present review explores the theoretical background of the implemented modifications and brings a panel of examples for WGE applications in high-throughput protein studies and synthesis of challenging-to-produce proteins such as protein complexes, extracellular proteins, and membrane proteins. It also highlights the unique advantages of in vitro translation as an open system for synthesising radioactively labelled proteins, as illustrated by numerous publications using WGE to meet the protein demands of these studies. This review aims to orientate readers in finding the most appropriate WGE arrangement for their specific needs and demonstrate that a deeper understanding of the system modifications will help them make further adjustments to the reaction conditions for synthesising difficult-to-express proteins.

In vitro co-expression chromatin assembly and remodeling platform for plant histone variants

Histone variants play a central role in shaping the chromatin landscape in plants, yet, how their distinct combinations affect nucleosome properties and dynamics is still largely elusive. To address this, we developed a novel chromatin assembly platform for Arabidopsis thaliana, using wheat germ cell-free protein expression. Four canonical histones and five reported histone variants were used to assemble twelve A. thaliana nucleosome combinations. Seven combinations were successfully reconstituted and confirmed by supercoiling and micrococcal nuclease (MNase) assays. The effect of the remodeling function of the CHR11-DDR4 complex on these seven combinations was evaluated based on the nucleosome repeat length and nucleosome spacing index obtained from the MNase ladders. Overall, the current study provides a novel method to elucidate the formation and function of a diverse range of nucleosomes in plants.

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

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.