Center for Molecular Spectroscopy and Dynamics

2018 BPS18

UnaG is a fluorogen-binding protein which only fluoresces upon binding of a small metabolite molecule, bilirubin (BR). Here we introduce a photo-switchable nature of UnaG originated from repetitive binding of BR under continuous light illumination. We found that the on-/off-switching rates are mainly controlled by the concentration of BR and the light intensity, respectively, where the dissolved oxygen also notably promotes the off-switching. With HPLC and LC/MS/MS studies, we proposed a full reaction scheme for the fluorescence switching of UnaG, including the photo-oxidation of BR. As a key application, we demonstrated super-resolution imaging based on single molecule localization with UnaG-expressing mammalian cells.

References

[1] A. Kumagai, R. Ando, H. Miyatake, P. Greimel, T. Kobayashi, Y. Hirabayashi, T. Shimogori, A. Miyawaki, Cell 2013, 153, 1602-1611.