title: Reactive cysteine is protonated in the triplet excited state of the LOV2 domain in Adiantum phytochrome3.
abstract: Phototropin is a plant blue-light sensor protein that possesses a flavin mononucleotide (FMN) as the chromophore in LOV domains. Its photoreaction is an adduct formation between FMN and a nearby cysteine that takes place in the triplet excited state of FMN. In this communication, we revealed that the reactive cysteine is protonated in the triplet excited state of the LOV2 domain of Adiantum phytochrome3 by means of low-temperature FTIR spectroscopy. Its hydrogen-bonding interaction is strengthened in the triplet excited state, presumably with the FMN chromophore. Such strong interaction drives adduct formation on a microsecond time scale.
authors.affiliation: Department of Materials Science and Engineering, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan.
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Sato
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Iwata
authors.forename: Satoru
authors.initials: S
authors.lastname: Tokutomi
authors.forename: Hideki
authors.initials: H
authors.lastname: Kandori
mesh_terms: D035681:Adiantum / Q000737:chemistry*; D003545:Cysteine / Q000737:chemistry*; D006860:Hydrogen Bonding; D010834:Phytochrome / Q000737:chemistry*; D017434:Protein Structure, Tertiary; D011522:Protons; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D011522:Protons; D010834:Phytochrome; D003545:Cysteine