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Issue 7, 2013
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Photochemistry of Arabidopsis phototropin 1 LOV1: transient tetramerization

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Abstract

The photochemical reaction of the LOV1 (light-oxygen-voltage 1) domain of phototropin 1 from Arabidopsis thaliana was investigated by the time-resolved transient grating method. As with other LOV domains, an absorption spectral change associated with an adduct formation between its chromophore (flavin mononucleotide) and a cysteine residue was observed with a time constant of 1.1 μs. After this reaction, a significant diffusion coefficient (D) change (D of the reactant = 8.2 × 10−11 m2 s−1, and D of the photoproduct = 6.4 × 10−11 m2 s−1) was observed with a time constant of 14 ms at a protein concentration of 270 μM. From the D value of the ground state and the peak position in size exclusion chromatography, we have confirmed that the phot1LOV1 domain exists as a dimer in the dark. The D-value and the concentration dependence of the rate indicated that the phot1LOV1 domain associates to form a tetramer (dimerization of the dimer) upon photoexcitation. We also found that the chromophore is released from the binding pocket of the LOV domain when it absorbs two photons within a pulse duration, which occurs in addition to the normal photocycle reaction. On the basis of these results, we discuss the molecular mechanism of the light dependent role of the phot1LOV1 domain.

Graphical abstract: Photochemistry of Arabidopsis phototropin 1 LOV1: transient tetramerization

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Publication details

The article was received on 12 Feb 2013, accepted on 14 May 2013 and first published on 15 May 2013


Article type: Paper
DOI: 10.1039/C3PP50047K
Citation: Photochem. Photobiol. Sci., 2013,12, 1171-1179
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    Photochemistry of Arabidopsis phototropin 1 LOV1: transient tetramerization

    Y. Nakasone, K. Zikihara, S. Tokutomi and M. Terazima, Photochem. Photobiol. Sci., 2013, 12, 1171
    DOI: 10.1039/C3PP50047K

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