Arraying proteins by cell-free synthesis

Expression, stabilization and purification of membrane proteins via diverse protein synthesis systems and detergents involving cell-free associated with self-assembly peptide surfactants

G-protein coupled receptors (GPCRs) are involved in regulating most of physiological actions and metabolism in the bodies, which have become most frequently addressed therapeutic targets for various disorders and diseases. Purified GPCR-based drug discoveries have become routine that approaches to structural study, novel biophysical and biochemical function analyses. However, several bottlenecks that GPCR-directed drugs need to conquer the problems including overexpression, solubilization, and purification as well as stabilization. The breakthroughs are to obtain efficient protein yield and stabilize their functional conformation which are both urgently requiring of effective protein synthesis system methods and optimal surfactants. Cell-free protein synthesis system is superior to the high yields and post-translation modifications, and early signs of self-assembly peptide detergents also emerged to superiority in purification of membrane proteins. We herein focus several predominant protein synthesis systems and surfactants involving the novel peptide detergents, and uncover the advantages of cell-free protein synthesis system with self-assembling peptide detergents in purification of functional GPCRs. This review is useful to further study in membrane proteins as well as the new drug exploration.

Firm wheat-germ cell-free system with extended vector usage for high-throughput protein screening

The wheat germ cell-free system is composed out of five basic steps, growth of Escherichia coli harboring plasmid, first colony-PCR, second PCR, transcription, and translation. Improvements of culture medium, colony based PCR, and modifications within the split primer set of the second PCR amplify both DNA and RNA levels. This yields more than 5 times increase in protein amount for pEU-originated templates. Especially, for the low PCR-amplifiable vectors with pET-origin, it leads to 30 fold higher product amount in translation. This broadens the range of usable vectors, overcoming the existing cell-free system limitations for high-throughput protein screening. Noteworthily, the system successfully maintains translation by S-30 cell-free extract below 30 OD. In conclusion, this improved firm cell-free system reduces cost and enables robotic automation and high-throughput thermodynamic analysis, especially for proteins that are difficult to be expressed.

Production of membrane proteins using cell-free expression systems

Production of membrane proteins (MPs) is a challenging task as their hydrophobic nature and their specific requirements in cellular expression systems frequently prevent an efficient synthesis. Cell-free (CF) expression systems have been developed in recent times as promising tools by offering completely new approaches to synthesize MPs directly into artificial hydrophobic environments. A considerable variety of CF produced MPs has been characterized by functional and structural approaches and the high success rates and the rapidly accumulating data on quality and expression efficiencies increasingly attract attention. In addition, CF expression is a highly dynamic and versatile technique and new modifications for improved performance as well as for extended applications for the labeling, throughput expression and proteomic analysis of MPs are rapidly emerging.