Figure 1.
Effects on AsLOV2 side chains during the photocycle.
(A) Side chain positions in the chromophore binding pocket in the dark and light state crystal structures [32] (B) Chemical processes that occur to the FMN chromophore during the photocycle.
Table 1.
Chromophore and Photocycle parameters of AsLOV2 variants.
Figure 2.
UV-Vis absorbance changes upon photoexcitation and recovery for selected AsLOV2 variants.
Single exponential fits to the time dependent data are shown in red.
Figure 3.
AsLOV2 structure and side chains near the chromophore.
(A) Location of side chains mutated in active-site cysteine variants (B) The effects of imidazole on photocycle lifetime in WT and C450V/Q513C.
Figure 4.
Photon absorption results in the FMN being excited into a singlet then triplet state. The N5 of FMN becomes a strong nucleophile and removes the proton from the nearby C450 to form a covalent bond with the FMN C4a atom. Reduction of the FMNH state is inhibited by the inability of water to readily enter the chromophore binding pocket and catalyze the transfer of the proton back to the cysteine until a conformational change occurs involving residues N414 and Q513. The covalent bond is broken and the protein returns to the dark state.