title: The LOV2 domain of phototropin: a reversible photochromic switch.
abstract: Light, oxygen, or voltage (LOV) domains constitute a new class of photoreceptor proteins that are sensitive to blue light through a noncovalently bound flavin chromophore. Blue-light absorption by the LOV2 domain initiates a photochemical reaction that results in formation of a long-lived covalent adduct between a cysteine and the flavin cofactor. We have applied ultrafast spectroscopy on the photoaccumulated covalent adduct state of LOV2 and find that, upon absorption of a near-UV photon by the adduct state, the covalent bond between the flavin and the cysteine is broken and the blue-light-sensitive ground state is regained on an ultrafast time scale of 100 ps. We thus demonstrate that the LOV2 domain is a reversible photochromic switch, which can be activated by blue light and deactivated by near-UV light.
authors.affiliation: Department of Biophysics, Faculty of Sciences, Vrije Universiteit, 1081HV Amsterdam, The Netherlands. j.kennis@few.vu.nl
authors.forename: John T M
authors.initials: JT
authors.lastname: Kennis
authors.forename: Ivo H M
authors.initials: IH
authors.lastname: van Stokkum
authors.forename: Sean
authors.initials: S
authors.lastname: Crosson
authors.forename: Magdalena
authors.initials: M
authors.lastname: Gauden
authors.forename: Keith
authors.initials: K
authors.lastname: Moffat
authors.forename: Rienk
authors.initials: R
authors.lastname: van Grondelle
mesh_terms: D035681:Adiantum / Q000737:chemistry; D056931:Cryptochromes; D003545:Cysteine / Q000737:chemistry; D029721:Drosophila Proteins; D005136:Eye Proteins; D005415:Flavins / Q000737:chemistry; D005420:Flavoproteins / Q000737:chemistry*; D017956:Photoreceptor Cells, Invertebrate; D010940:Plant Proteins / Q000737:chemistry*; D017434:Protein Structure, Tertiary; D043562:Receptors, G-Protein-Coupled; D013056:Spectrophotometry, Ultraviolet
chemical_list: D056931:Cryptochromes; D029721:Drosophila Proteins; D005136:Eye Proteins; D005415:Flavins; D005420:Flavoproteins; D010940:Plant Proteins; D043562:Receptors, G-Protein-Coupled; C119828:cry protein, Drosophila; D003545:Cysteine