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Automated production of functional membrane proteins using eukaryotic cell-free translation systems

: Quast, Robert B.; Kortt, Oliver; Henkel, Jörg; Dondapati, Srujan K.; Wüstenhagen, Doreen A.; Stech, Marlitt; Kubick, Stefan

Fulltext ()

Journal of biotechnology 203 (2015), pp.45-53
ISSN: 0168-1656
ISSN: 1389-0352
ISSN: 1873-4863
Journal Article, Electronic Publication
Fraunhofer IZI ()
automation; electrophysiology; eukaryotic cell-free protein synthesis; fluorescence modification; integral membrane protein; non-canonical amino acid

Due to their high abundance and pharmacological relevance there is a growing demand for the efficient production of functional membrane proteins. In this context, cell-free protein synthesis represents a valuable alternative that allows for the high-throughput synthesis of functional membrane proteins. Here, we demonstrate the potential of our cell-free protein synthesis system, based on lysates from cultured Spodoptera frugiperda 21 cells, to produce pro- and eukaryotic membrane proteins with individual topological characteristics in an automated fashion. Analytical techniques, including confocal laser scanning microscopy, fluorescence detection of eYFP fusion proteins in a microplate reader and in-gel fluorescence of statistically incorporated fluorescent amino acid derivatives were employed. The reproducibility of our automated synthesis approach is underlined by coefficients of variation below 7.2%. Moreover, the functionality of the cell-free synthesized potassium channel KcsA was analyzed electrophysiologically. Finally, we expanded our cell-free membrane protein synthesis system by an orthogonal tRNA/synthetase pair for the site-directed incorporation of p-Azido-l-phenylalanine based on stop codon suppression. Incorporation was optimized by performance of a two-dimensional screening with different Mg2+ and lysate concentrations. Subsequently, the selective modification of membrane proteins with incorporated p-Azido-l-phenylalanine was exemplified by Staudinger ligation with a phosphine-based fluorescence dye.