Glutamate Biosensor Based on Chimeric Two-Component Regulatory System Introduced into Escherichia coli

This study describes the construction of specific amino acid biosensors, which can be used as a high throughput screening system to screen microorganism producing glutamate. The biosensors are based on the chimeric two-component regulatory systems (TCRS). A chimeric DegS/EnvZ (DegSZ) TCRS was constructed by fusing the sensor kinase of DegS from Planococcus sp. PAMC21323 with the cytoplasmic signaling domain of the E.coli osmosensor EnvZ to control the expression of the gfp gene in response to glutamate.  The gfp gene was mediated by the ompC gene promoter through the response regulator, OmpR. The biosensors showed a 4-fold increase of the Fluorescent signal after addition of glutamate. The linear correlation was observed between the Fluorescence intensity and exogenously added glutamate concentration. The chimeric TCRS based biosensor was successfully applied for detection of glutamate concentration at the single cell level by Fluorescence-activated cell sorting. Therefore We beleive this biosensors can be used to isolate novel gene products and optimize pathways involved in amino acid production.