title: Proton-Coupled Electron Transfer Constitutes the Photoactivation Mechanism of the Plant Photoreceptor UVR8.
abstract: UVR8 is a novel UV-B photoreceptor that regulates a range of plant responses and is already used as a versatile optogenetic tool. Instead of an exogenous chromophore, UVR8 uniquely employs tryptophan side chains to accomplish UV-B photoreception. UV-B absorption by homodimeric UVR8 induces monomerization and hence signaling, but the underlying photodynamic mechanisms are not known. Here, by using a combination of time-resolved fluorescence and absorption spectroscopy from femto- to microseconds, we provide the first experimental evidence for the UVR8 molecular signaling mechanism. The results indicate that tryptophan residues at the dimer interface engage in photoinduced proton coupled electron transfer reactions that induce monomerization.
authors.affiliation: †Biophysics Section, Department of Physics and Astronomy, Faculty of Sciences, VU University, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands.
authors.forename: Tilo
authors.initials: T
authors.lastname: Mathes
authors.affiliation: ‡Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, Bower Building, University of Glasgow, Glasgow G12 8QQ, United Kingdom.
authors.forename: Monika
authors.initials: M
authors.lastname: Heilmann
authors.affiliation: †Biophysics Section, Department of Physics and Astronomy, Faculty of Sciences, VU University, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands.|§Department of Solid-State NMR, Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands.
authors.forename: Anjali
authors.initials: A
authors.lastname: Pandit
authors.affiliation: †Biophysics Section, Department of Physics and Astronomy, Faculty of Sciences, VU University, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands.
authors.forename: Jingyi
authors.initials: J
authors.lastname: Zhu
authors.affiliation: †Biophysics Section, Department of Physics and Astronomy, Faculty of Sciences, VU University, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands.
authors.forename: Janneke
authors.initials: J
authors.lastname: Ravensbergen
authors.affiliation: †Biophysics Section, Department of Physics and Astronomy, Faculty of Sciences, VU University, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands.
authors.forename: Miroslav
authors.initials: M
authors.lastname: Kloz
authors.affiliation: ‡Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, Bower Building, University of Glasgow, Glasgow G12 8QQ, United Kingdom.
authors.forename: Yinan
authors.initials: Y
authors.lastname: Fu
authors.affiliation: ‡Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, Bower Building, University of Glasgow, Glasgow G12 8QQ, United Kingdom.
authors.forename: Brian O
authors.initials: BO
authors.lastname: Smith
authors.affiliation: ‡Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, Bower Building, University of Glasgow, Glasgow G12 8QQ, United Kingdom.
authors.forename: John M
authors.initials: JM
authors.lastname: Christie
authors.affiliation: ‡Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, Bower Building, University of Glasgow, Glasgow G12 8QQ, United Kingdom.
authors.forename: Gareth I
authors.initials: GI
authors.lastname: Jenkins
authors.affiliation: †Biophysics Section, Department of Physics and Astronomy, Faculty of Sciences, VU University, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands.
authors.forename: John T M
authors.initials: JT
authors.lastname: Kennis
mesh_terms: D017360:Arabidopsis / Q000737:chemistry*; D029681:Arabidopsis Proteins / Q000737:chemistry*; D002868:Chromosomal Proteins, Non-Histone / Q000737:chemistry*; D004579:Electron Transport; D004583:Electrons; D008027:Light; D008958:Models, Molecular; D055668:Photochemical Processes; D055503:Protein Multimerization; D011522:Protons; D013050:Spectrometry, Fluorescence
chemical_list: D029681:Arabidopsis Proteins; D002868:Chromosomal Proteins, Non-Histone; D011522:Protons; C525052:Uvr8 protein, Arabidopsis