Structural basis for the photoconversion of a phytochrome to the activated far-red light-absorbing form

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Issue Date
2010-01-14Author
Ulijasz, Andrew T.
Cornilescu, Gabriel
Cornilescu, Claudia C.
Zhang, Junrui
Rivera, Mario
Markley, John L.
Vierstra, Richard D.
Publisher
Nature Publishing Group
Type
Article
Article Version
Scholarly/refereed, author accepted manuscript
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Show full item recordAbstract
Phytochromes are a collection of bilin-containing photoreceptors that regulate numerous photoresponses in plants and microorganisms through their ability to photointerconvert between a red light-absorbing, ground state Pr and a far-red light-absorbing, photoactivated state Pfr1,2. While the structures of several phytochromes as Pr have been determined3-7, little is known about the structure of Pfr and how it initiates signaling. Here, we describe the three-dimensional solution structure of the bilin-binding domain as Pfr using the cyanobacterial phytochrome from Synechococcus OSB’. Contrary to predictions, light-induced rotation of the A but not the D pyrrole ring is the primary motion of the chromophore during photoconversion. Subsequent rearrangements within the protein then affect intra- and interdomain contact sites within the phytochrome dimer. From our models, we propose that phytochromes act by propagating reversible light-driven conformational changes in the bilin to altered contacts between the adjacent output domains, which in most phytochromes direct differential phosphotransfer.
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Citation
Ulijasz, A. T., Cornilescu, G., Cornilescu, C. C., Zhang, J., Rivera, M., Markley, J. L., & Vierstra, R. D. (2010). STRUCTURAL BASIS FOR THE PHOTOCONVERSION OF A PHYTOCHROME TO THE ACTIVATED FAR-RED LIGHT-ABSORBING FORM. Nature, 463(7278), 250–254. http://doi.org/10.1038/nature08671
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