Insights into the photoswitch based on 5-deazaFMN and LOV2 from Avena sativa : a combined absorption and NMR spectroscopy study

The LOV2 domain from ( ) is a blue light receptor that undergoes adduct formation with the native flavin mononucleotide (FMN) cofactor [Salomon , , 2000, , 9401]. We report the photochemical changes of LOV2 through cofactor exchange with the FMN analogue 5-deazaFMN. Absorption spectroscopy shows that upon illumination a thermodynamically stable adduct is formed. We were able to confirm the structure of the adduct by introducing C-labelled 5-deazaFMN isotopologues in solution NMR experiments. Dark-adapted state recovery can be photo-induced, providing a photoswitch that is easy to manipulate. The robust photocycle is repeatable without significant loss. Based on the data presented we propose the system as an alternative to wild-type LOV2 for applications in optogenetics.