Nito K, Wong CCL, Yates JR, Chory J. Tyrosine phosphorylation regulates the activity of phytochrome photoreceptors.
Cell Rep 2013;
3:1970-9. [PMID:
23746445 DOI:
10.1016/j.celrep.2013.05.006]
[Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Revised: 05/03/2013] [Accepted: 05/06/2013] [Indexed: 10/26/2022] Open
Abstract
Phytochromes are red/far-red light receptors that function in photomorphogenesis of plants. Photoisomerization of phytochrome by red light leads to its translocation to the nucleus, where it regulates gene expression. We examined whether phytochrome is phosphorylated in response to light, and we report that phytochrome B (phyB)'s N terminus contains a region with a number of phosphoserines, threonines, and tyrosines. The light-dependent phosphorylation of tyrosine 104 (Y104) appears to play a negative role in phyB's activity, because a phosphomimic mutant, phyBY104E, is unable to complement any phyB-related phenotype, is defective in binding to its signaling partner PIF3, and fails to form stable nuclear bodies even though it retains normal photochemistry in vitro. In contrast, plants stably expressing a nonphosphorylatable mutant, phyBY104F, are hypersensitive to light. The proper response to changes in the light environment is crucial for plant survival, and our study brings tyrosine phosphorylation to the forefront of light-signaling mechanisms.
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