Abstract
A sensor of blue light using FAD (BLUF) protein is a new family of blue light sensory protein using FAD as a chromophore. It has been proposed that light signal acquired by FAD is transformed into structural changes of protein for the signaling state, through rearrangement of hydrogen bond network, involving FAD isoalloxazine ring. In this study, a BLUF domain of AppA was in vitro reconstituted from non-labeled apo-protein and isotope edited FAD, in which each C or N atom of the isoalloxazine ring was selectively labeled with 13C or 15N. The labeling induced the isotope shift of the specific IR bands in the light-induced Fourier transform infrared (FTIR) spectrum. The results enable us to assign respective IR bands, and, therefore, allow us to evaluate details of the light-induced structural changes for the signaling state in the BLUF domain.
