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United States Department of Agriculture

Agricultural Research Service

Title: Binding of Phytochrome B to Its Nuclear Signaling Partner Pif3 Is Reversibly Inducted by Light

Authors
item Quail, Peter - ARS-UCB PLNT GENE EXP CTR
item Ni, M. - ARS-UCB PLNT GENE EXP CTR
item Tepperman, J. - ARS-UCB PLNT GENE EXP CTR

Submitted to: Nature
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 9, 1999
Publication Date: August 19, 1999
Citation: Quail, P.H., Ni, M., Tepperman, J.M. 1999. Binding of phytochrome b to its nuclear signaling partner pif3 is reversibly inducted by light. Nature 400:781-784.

Interpretive Summary: We show that full-length photoactive phytochrome B binds PIF3 in vitro only upon light-induced conversion to its active form, and that photoconversion back to its inactive form causes dissociation from PIF3.

Technical Abstract: The phytochrome photoreceptor family directs plant gene expression by switching between biologically inactive and active conformers in response to the sequential absorption of red and farred photons. Several intermediates that act late in the phytochrome signalling pathway have been identified, but fewer have been identified that act early in the pathway. We have cloned a nuclear basic helix-loop-helix protein, PIF3, which can bind to non-photoactive carboxy-terminal fragments of phytochromes A and B and functions in phytochrome signalling in vivo. Here we show that full-length photoactive phytochrome B binds PIF3 in vitro only upon light-induced conversion to its active form, and that photoconversion back to its inactive form causes dissociation from PIF3. We conclude that photosensory signalling by phytochrome B involves light-induced, conformer-specific recognition of the putative transcriptional regulator PIF3, providing a potential mechanism for direct photoregulation of gene expression.

Last Modified: 12/24/2014
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