Development of Cell immobilization method by using cell surface displayed gold-binding proteins

Abstract

A whole-cell biosensor can obtain functional information about the effect of a stimulus on a living system and detect various chemical compounds. The immobilization technology stabilizing living cells on the surface is a significant factor for the construction of a whole-cell biosensor. For the efficient cell immobilization, gold-binding proteins (GBP) were displayed on the E. coli cell surface using a FadL outer membrane as an anchoring motif. The colorimetric and spectrometric methods were carried out to confirm the display of GBP. GBP-displaying cells were immobilized onto the gold surface and subsequently detected by a SPR measurement and an optical microscopy. Also, the degree of binding affinity by the concentration of cells and the repeating number of GBP was checked and pH study was carried out to find out the optimal binding condition. We confirmed that GBP-displaying cells were very stably immobilized on the gold surface for the long time. In addition, streptavidin was displayed on the same cell using an OprF outer membrane protein. Interaction between biotin-HRP and CSA displayed on the immobilized cells was detected by a SPR analysis to check the dual-display system and the potential ability as a biosensor. This dual-display system is not only the first approach in E. coli but also novel try for the efficient cell immobilization.