Engineering a molecular light switch in E. coli

Photoreceptors are utilized by almost every organism to adapt to their ambient light environment. Bacteriophytochrome (Bph) photoreceptors are a member of the phytochrome superfamily (phy). Bph photoreceptors can detect the light surrounding the bacteria and can respond by changing its conformational structure according to the changing light environment. Light detection is achieved by rapid photo-conversion between two stable isoforms of Bphs; red light-absorbing Pr form and far-red light-absorbing Pfr form. In this study, we engineer a novel, reversible molecular ‘light switch’ within E. coli by introducing a photoreceptor from non-photosynthetic bacteria (Deinococcus radiodurans and Agrobacterium tumafaciens). By cloning the bacteriophytochrome coupled with heme-oxygenase, an enzyme producing biliverdin, the created colonies are able to respond to red and far-red light environments. This novel approach will result in the colour of E. coli to ‘switch’ from blue to green reversibly. E. coli chameleon will serve as a fundamental “Biobrick” for many biomolecular applications by providing a convenient and photo-reversible switch system. Here in this study, we report expression of engineered Bph in E. coli and demonstrate in vivo assembly of Bph with biliverdin within E. coli.