Abstract
Phototropin is a plant blue-light sensor protein that possesses a flavin mononucleotide (FMN) as the chromophore. Upon light absorption, structural changes of the FMN-binding LOV domain activate serine/threonine kinase domain, leading eventually to various functions such as tropic responses, relocation of chloroplast, and stomata opening in plants.
Phototropin is a water-soluble protein. Therefore hydration conditions are presumed to affect structural change of LOV domains. Recently, we found that hydration condition significantly affected light-induced structural change of Phy3-LOV2 by means of FTIR spectroscopy. Structural changes of secondary structures, such as α-helices and β-sheets, depend on hydration volume. Furthermore, the decay of the S390, intermediate, also depends on hydration volume. From these results, it is concluded that hydration is necessary for the structural change of Phy3-LOV2, which probably causes protein fluctuation for conformation transition of protein.
