Mühle M, Löchelt M, Denner J (2011): Optimisation of expression and purification of the feline and primate foamy virus transmembrane envelope proteins using a 96 deep well screen.
Protein Expr. Purif.: Epub Sep 22. doi: 10.1016/j.pep.2011.09.006.

The production of recombinant transmembrane proteins is due to their biochemical properties often troublesome and time consuming. Here the prokaryotic expression and purification of the transmembrane envelope proteins of the feline and primate foamy virus using a screening assay for optimisation of expression in 96 deep well plates is described. Testing simultaneously various bacterial strains, media, temperatures, inducer concentrations and different transformants, conditions for an about twentyfold increased production were quickly determined. These small scale test conditions could be easily scaled up, allowing purification of milligram amounts of recombinant protein. Proteins with a purity of about 95% were produced using a new purification protocols, they were characterised by gel filtration and circular dichroism and successfully applied in immunological assays screening for foamy virus infection and in immunisation studies. Compared to the previously described protocol (Muehle et al., Virology, 412:333-340, 2011), proteins with similar characteristics but about thirtyfold increased yields were obtained. The screening and production method presented here can also be applied for the production of transmembrane envelope proteins of other retroviruses, including HIV-1.