Enhanced expression of recombinant proteins inEscherichia coliby co-expression withVibrio parahaemolyticusCsgG, a pore-forming protein of the curli biogenesis pathway

摘要

Aim To test whether engineered nanopores on the outer membrane (OM) ofEscherichia colican increase expression of heterologous proteins by making additional nutrients available to the host. Methods and Results Outer membrane nanopores were generated by expressing recombinantVibrio parahaemolyticusCsgG (rVpCsgG), which spontaneously assembles into a pore-forming channel on the OM, allowing spontaneous diffusion of small chemical entities from the exterior. Protein expression was probed using a reporter protein, sfGFP, expressed on a second compatible plasmid. OM pore formation was shown by acquired erythromycin sensitivity in cells transformed with rVpCsgG, influx of propidium iodide as well as by surface localization of recombinant CsgG by immunogold-labeled transmission electron microscopy. Expression of recombinant CsgG showed increased growth and also enhanced expression of sfGFP in minimal medium and is due to both enhanced transcription as well as translation. Similar enhancement of expression was also observed for a number of different proteins of different origin, sizes and nature. Conclusions Our findings clearly demonstrate that engineered nanopores on the OM ofE. colienhance expression of different heterologous proteins in minimal medium. Significance and Impact of the Study Vibrio parahaemolyticusCsgG beta-nanopore mediated co-expression strategy to improve recombinant protein expression is fully compatible with other methods of protein expression enhancement, and therefore can be a useful tool in biotechnology particularly for whole-cell bio-transformations for production of secondary metabolite.