Abstract
LOV domains function as blue light sensing modules in various photoreceptors found in plants, fungi, algae and bacteria. PAS/LOV protein (PLP) consisting of a PAS domain and a LOV domain has been found from Arabidopsis thaliana and Solanum lycopersicum as a LOV domain-containing protein although its function remains unknown. When expressed in Escherichia coli, SlPLP binds FMN and undergoes a self-contained photocycle upon irradiation of blue light. The C295A mutation in the LOV domain caused the complete loss of photocycle. These results are consistent with the light-induced formation of a cysteinyl adduct to the FMN chromophore in SlPLP. Analyses using mutant SlPLPs revealed that SlPLP binds FMN in the PAS domain as well as in the LOV domain. This study reveals that plants have a new LOV domain-containing protein having typical biochemical and photochemical properties of other LOV domain-containing protein such as phototropins.
