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Proton-Coupled Electron Transfer Constitutes the Photoactivation Mechanism of the Plant Photoreceptor UVR8
journal contribution
posted on 2015-12-22, 22:41 authored by Tilo Mathes, Monika Heilmann, Anjali Pandit, Jingyi Zhu, Janneke Ravensbergen, Miroslav Kloz, Yinan Fu, Brian O. Smith, John M. Christie, Gareth I. Jenkins, John T. M. KennisUVR8 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.