Alpha Lifetech Inc. focuses on recombinant protein expression in different Biosystems for many years, including prokaryotic and eukaryotic organisms, as well as the development of novel high-potency recombinant proteins.

Single Protein Production （SPP system） in Cell Bioreactor

What is the SPP system? The single protein production system is designed to produce only a single protein of interest in living Escherichia coli cells or other species cells. The gene, MazF encoding an mRNA interferase that cleaves RNA at ACA nucleotide sequences, results in complete cell growth arrest and high accumulation of target protein in the plasm of the host. Because we'll modify the mRNA encoding a protein of interest by substituting ACA base triplets with other ones, and then integrate this mRNA into the special vector (as described above) that can be induced to express the target protein at a low temperature (stress condition) in MazF-expressing cells. Only the protein from this mRNA is produced at a yield of 20–30% of total cellular protein; other cellular protein synthesis is almost completely absent.

What can we do?

The expression of toxic proteins, such as membrane proteins (MPs), GPCRs and ion channels proteins, is a challenging task as their hydrophobic nature and their specific requirements in cellular expression systems frequently prevent an efficient synthesis. Conventional methods, such as Mammal Expression System, Insect Expression System, Bacteria Expression System and Yeast Expression System, have intrinsic limitations to produce these proteins in vivo or vitro. To create a high-yield and soluble protein, Alpha Lifetech Inc. has created and optimized a powerful tool to express various proteins in cell bioreactors. We yield proteins in the cell bioreactors (E. coli or other species) by creating a temperature- and chemical-induced vector system which contains the cspA (cold-shock protein) promoter and Lac promoter that could regulate the proliferation of cells and expression of target proteins in conditions.

In addition, the SPP system has a strong advantage to express and label the protein of interest for structure study, since we use chemical-defined mediums to culture cells. In this case, this system could be used efficiently to label proteins by isotopes (15N, 13C and 35S), amino acid analogs and selenomethionine.

Moreover, Alpha Lifetech Inc. also created several cell-free expression systems to express proteins with special requirements: