Cryptochromes are blue/ultraviolet-A light receptors that mediate various light responses in plants and animals1,2. But the initial photochemical reaction of cryptochrome is still unclear. For example, although most photoreceptors are known to undergo light-dependent protein modification such as phosphorylation3,4, no blue-light dependent phosphorylation has been reported for a cryptochrome. Arabidopsis cryptochrome 2 (cry2) mediates light regulation of seedling development and photoperiodic flowering5,6. The physiological activity and cellular level of cry2 protein are light-dependent5,6,7,8, and protein–protein interactions are important for cry2 function9,10. Here we report that cry2 undergoes a blue-light-dependent phosphorylation, and that cry2 phosphorylation is associated with its function and regulation. Our results suggest that, in the absence of light, cry2 remains unphosphorylated, inactive and stable; absorption of blue light induces the phosphorylation of cry2, triggering photomorphogenic responses and eventually degradation of the photoreceptor.
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We thank T. Cashmore, X.-W. Deng, J. Chory and T. Kretsch for providing Arabidopsis mutant lines. This work is supported by research grants from the National Institutes of Health, the National Science Foundation and UCLA-FGP. T.C.M. is supported by a predoctoral UCLA-NSF/IGERT training award.
The authors declare that they have no competing financial interests.
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Shalitin, D., Yang, H., Mockler, T. et al. Regulation of Arabidopsis cryptochrome 2 by blue-light-dependent phosphorylation. Nature 417, 763–767 (2002). https://doi.org/10.1038/nature00815
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